TOKYO — Sydney McLaughlin recently said that “iron sharpens iron” when it comes to her relationship with Dalilah Muhammad. They are the pre-eminent practitioners of their craft, the two fastest women ever to run the 400-meter hurdles.

Few events were more highly anticipated at the Tokyo Games than the renewal of their rivalry on Wednesday at Olympic Stadium.

It was safe to assume that something extraordinary would happen, and McLaughlin delivered, breaking her own world record to win her first Olympic gold.

McLaughlin, 21, finished in 51.46 seconds. Muhammad ran the fastest time of her life to take the silver medal in 51.58 seconds, and Femke Bol of the Netherlands was third.

There have been various high-profile chapters between McLaughlin and Muhammad. At the 2019 world championships, Muhammad dipped under her own world record to edge McLaughlin for the win.

But at the U.S. Olympic trials in June, McLaughlin — so often considered the prodigy — met the outsize expectations that had shadowed her since she was a teenager by breaking Muhammad’s world record. Muhammad, after dealing with injuries and illness during the pandemic, finished second at the trials.

Those two races, though, were preludes to what played out on Wednesday, the fastest women’s 400-meter hurdles race in history — one day after Karsten Warholm of Norway won gold in the fastest men’s 400-meter hurdles race in history.

Muhammad, 31, who had come to Tokyo as the reigning Olympic champion, went out hard to take an early lead. But McLaughlin was gaining on her coming off the final turn and out-sprinted her in the final meters.

McLaughlin was a teenager when she competed at the 2016 Olympics in Rio de Janeiro, where she fell short of advancing to the final. It was a learning experience, and she leaned on some of those lessons in Tokyo. The Olympics were not new to her. She seemed utterly unfazed by it all.

She had spent the early part of the year refining her technique by running the 100-meter hurdles at the behest of her coach, Bob Kersee. The idea, McLaughlin said, was to “feel the rhythm of running faster.”

On Wednesday, she was the fastest in the world.

TOKYO — Sky Brown, the 13-year-old skateboarder who grew up in Japan, lives in California and is competing for Britain, is trying to become the youngest officially recognized gold medalist in Olympics history.

So is 12-year-old Kokona Hiraki of Japan.

Both of them cruised through preliminary heats for the women’s park discipline under the blistering sun at Ariake Urban Sports Park on Wednesday morning. They are headed to the afternoon final along with six others, including Misugu Okamoto, 15, and Sakura Yosozumi, 19, both of Japan.

Bryce Wettstein of the United States, 17, qualified in fifth place to reach the final, too.

The women’s park discipline in skateboarding had the youngest set of teenagers (and one preteen) in the Olympics, and they grinded and wove their way before empty grandstands and a global television audience.

One by one, the women skateboarders — most of them quite young women — dropped into the concrete bowl and buzzed over its bumps and up its walls, flying up and over the lip to twist and turn and drop back in again.

Brown, Hiraki and Okamoto were among those who stood out from the others, with bigger airs, more nuanced tricks and an air of confidence.

When the final ends, it is possible that the Olympics will have its youngest-ever gold medalist. The distinction currently belongs to Marjorie Gestring, a diver who won at age 13 years and 268 days at the 1936 Berlin Games.

Hiraki is the second-youngest athlete among the 11,000 at these Olympics. She wore white Nike coveralls, like someone about to go painting, and turns 13 in about three weeks. (The youngest Olympian competing in Tokyo was Hend Zaza of Syria, a table-tennis player.)

Brown turned 13 last month. She is the effervescent daughter of a British father and Japanese mother, who grew up mostly in Japan and now lives mostly in Southern California.

“All three of them feel like home,” she said.

She gained notoriety in Britain by winning a juniors version of “Dancing With the Stars” in 2018. Her smile and Instagram posts have earned her fans in at least three countries. She has a younger brother named Ocean who has gained attention, too.

She was severely injured last year in an accident at Tony Hawk’s indoor skatepark when she flew through a gap in two high ramps, crashing at least 15 feet to the concrete. She was unconscious with a skull fracture and broke her wrist and hand. A chipped tooth was repaired this spring.

“I was dead — well, not dead, but knocked out for, like, 16 hours,” she said in an interview in May.

She was back on a board a few weeks later, and appears to be flying higher and skating harder than ever.

“Falling is part of skateboarding,” she said. “It’s part of life. I was honestly excited to get back on the board.”

Brown’s main rival at the Olympics was expected to be Okamoto, a quiet and straight-faced competitor, the best park skater of the past couple of years. She leads a deep Japanese contingent that has captured more medals in skateboarding than any other country.

Skateboarding was added to the Olympics for just this reason — to add a jolt of youthful energy. It was especially true among the women. In the Olympic street discipline last week, the gold, silver and bronze medals went to young women aged 13, 13 and 16. It was celebrated as the start of a new generation.

But those results were a surprise. Park is where the medal stand was expected to elevate youth. In all, 11 of the 20 athletes in women’s park were teenagers, and a 12th, Hiraki, is not quite there yet.

Here are some highlights of U.S. broadcast coverage on Tuesday evening. All times are Eastern.

GOLF NBC Golf airs the first round of play in the women’s tournament live at 6:30 p.m.

TRACK AND FIELD Coverage begins at 8 p.m. on USA Network, with highlights including a replay of the women’s 200-meter and 800-meter races. The men’s 110-meter hurdles semifinals will be broadcast live starting at 10 p.m., and the highly anticipated women’s 400-meter hurdles final starts at 10:30 p.m. Heats for the decathlon, heptathlon and men’s javelin will be held.

WATER POLO The U.S. women’s team faces Canada in a quarterfinal match that will be replayed on NBCSN at 8 p.m. The U.S. men play Spain in a quarterfinal game at 2 a.m. on CNBC.

GYMNASTICS NBC will air replays of the men’s horizontal bar final and the women’s beam final starting at 9 p.m.

SOCCER The men’s teams from Mexico and Brazil face off in a semifinal game replayed at 9 p.m. on NBCSN.

SKATEBOARDING The women’s park competition kicks off at 9 p.m. on CNBC, with the finals airing live at 11:30 p.m.

WRESTLING Men compete in the round of 16 and quarterfinal matches for freestyle in the 57-kilogram and 86-kilogram weight classes. Women face off in the 57-kilogram class for freestyle. Coverage starts at 10 p.m. on the Olympic Channel.

BASKETBALL The N.B.A. superstar Kevin Durant leads the United States men’s team against Spain, with Pau Gasol, at 10:45 p.m. on USA Network. The women’s team, featuring Sue Bird and Diana Taurasi, plays Australia at 12:40 a.m. on USA Network in a live broadcast.

BASEBALL The U.S. team faces the Dominican Republic in an elimination game airing live at 12:15 a.m. on CNBC.

The major contenders Sky Brown of Britain and Kokona Hiraki of Japan are bidding for gold in the park skateboard competition on Wednesday. If either wins, she would achieve another distinction: the youngest-ever Olympic gold medalist.

Or would she?

The current accepted youngest gold medalist is Marjorie Gestring, a 13-year-old American diver who won the springboard competition in 1936. Her record was threatened by Momiji Nishiya of Japan, a 13-year-old who won the street skateboard competition last week. But Nishiya was about two months older than Gestring was at the time of her gold.

However, either Hiraki, 12, or Brown, who is 13 but younger than Gestring was, would break the record.

The youngest medalist of any color was Dimitrios Loundras, a Greek who at age 10 in 1896 won a bronze medal in team gymnastics

But there’s one possible snag to Brown or Hiraki getting the record.

At the Paris Games of 1900, a Dutch rowing pair recruited a local French boy to be their coxswain. After they won, he disappeared into the crowd. Though several candidates have been put forward, his identity has never been discovered and remains one of the greatest mysteries in Olympic history.

The consensus is that he was 10 or younger, but despite the avid interest of Olympics researchers for years, that simply isn’t known for sure.

On Sunday, Raven Saunders won a silver medal in the shot-put at the Tokyo Games. On Tuesday, NBC reported that her mother had died in Orlando, Fla., where she had gone to attend an Olympic watch party for her daughter.

Saunders called her mother, Clarissa Saunders, her “number one guardian angel” in a message on Twitter.

Herbert Johnson, Raven Saunders’s longtime coach, confirmed her mother’s death in a Facebook post. He said that Clarissa Saunders and Raven’s sister, Tanzy, had gone from Charleston, S.C., the Saunders family’s hometown, to Orlando to watch Raven compete in the Olympics.

Raven Saunders did not disappoint. Sporting hair dyed green on the right and purple on the left and a mask that was a nod either to the Joker or the Hulk (her nickname), she defeated all competitors but Gong Lijiao of China.

Saunders, 25, brought attention to her feat, dancing and singing “Celebration” afterward and later, on the medals podium, crossing her arms in the shape of an X, a gesture she said was “for oppressed people.”

“Not being there is a bummer,” Clarissa Saunders said of not being able to be with her daughter in Tokyo, The State, a newspaper in Columbia, S.C., reported. “But hey, we’re cheering from here … and she knows we’re here cheering for her.”

Saunders, who finished fifth in the shot-put in the 2016 Rio Games, has publicly praised her mother for her support. In an Instagram post on Mother’s Day, Saunders said of her mother: “You’ve shown me what strength is and for that I can push through anything. You’ve shown me relentlessness and for that I’ve learned determination.”

Mayor John Tecklenburg of Charleston called Clarissa Saunders “Raven’s strongest supporter.”

“On behalf of the citizens of Charleston, we pray for Raven and her family, and join them in grieving this unimaginable loss,” Mr. Tecklenburg said in a statement.

CHIBA, Japan — Either way on Tuesday night, Tamyra Mensah-Stock knew there would be a first.

Since women’s wrestling was added to the Summer Olympics in 2004, a Black woman had never won the top prize. But in the light heavyweight gold medal match at Makuhari Messe Hall, Mensah-Stock, a Texas native whose father came to the United States from Ghana at 30, was going up against Blessing Oborududu of Nigeria.

“Oooooh, it was awesome,” Mensah-Stock said afterward with her usual zeal and earnestness.

“Oh my gosh, look at us representing,” she added later. “And I’m like, if one of us wins, we’re making history. You’re making history, I’m making history, we’re making history. It’s fantastic. It meant a lot. I’m so proud of Blessing. I was looking at her, ‘Dang, she’s killing it.’ But I can kill it, too.”

And Mensah-Stock, 28, certainly did, dominating her opponents throughout the Tokyo Games and beating Oborududu, 32, by a score of 4-1 to become the second American woman to win a wrestling gold medal after Helen Maroulis in 2016.

Asked about the feat after the match, she said: “Young women are going to see themselves in a number of ways. And they’re going to look up there and go: ‘I can do that. I can see myself.’”

Then Mensah-Stock signaled toward her head, saying: “Look at this natural hair. Come on, man! I made sure I brought my puffballs out so they could know that you can do it, too.”

Serving as a symbol to others has long been on Mensah-Stock’s mind. Back home in Katy, Texas, she started wrestling in 10th grade after she was bullied in track and field, her sport of choice. She reluctantly switched to wrestling at the behest of her twin sister, a wrestler, but soon found that the sport not only unlocked her athletic ability but also helped her develop confidence.

Mensah-Stock said she wanted other young women, perhaps those who felt as she once did, to see that “you can be silly, you can have fun, and you can be strong, you can be tough and you can be a wrestler.”

In her first year wrestling, Mensah-Stock finished second in the state championships but knew more was to come. She told a friend that they would be Olympians one day. In 2016, she made it to the Rio Games, but only as a practice partner for her teammates when she failed to secure a spot in the competition.

“From the very beginning, I knew I could get here,” she said.

Although a Black woman hadn’t won an Olympic gold in wrestling before, Mensah-Stock rattled off the names of Black wrestlers who had achieved so much before her. Among them: Toccara Montgomery, who finished seventh in the 2004 Games, and Randi Miller, who won a bronze medal in the 63-kilogram weight class in 2008.

“They paved the way for me, and I was like, ‘I know you guys could have done it, so I’m going out there and I’m going to accomplish this,’” Mensah-Stock said.

Before the gold medal match, Mensah-Stock struggled to sleep because of nerves. She said her coach, Izzy Izboinikov, made sure she ate something. Watching other wrestlers from the United States compete earlier on Tuesday made her anxiety worse.

“It wasn’t pretty,” she said.

But after the clock ran out and Mensah-Stock was the winner, she formed a heart sign with her hands and showed it to both sides of the arena. The television broadcast showed her family, watching from the United States, making the same gesture in response. From the stands, her training partner Maya Nelson clapped and shouted with so much glee that her mask couldn’t stay on.

The heart sign, she later said, was a tribute to her loved ones: her father who died in a car crash after leaving one of her high school tournaments, a tragedy that nearly led her to quit wrestling; her uncle, a former professional boxer, who died of cancer; her grandfather who also died of cancer; a late friend who was also a wrestler; her husband, her mother, her aunt, her sister and the entire country.

“I’m trying to send love to everyone,” she said.

It is not just that India was once the best team in the world in field hockey. It’s that India was once better at field hockey than any country was at nearly anything.

Those glory days had seemed to be long gone. India, which once won hockey medals at 10 straight Olympics, has not touched one since 1980. But at these Olympics, the Indian men’s hockey team has raised echoes of the great teams of the past, and the women’s team, which has never won a medal, is in contention for the first time.

The men’s gold medal bid came to an end on Tuesday with a 5-2 loss to Belgium in the semifinals, but the team still had a chance for a bronze, its best performance in a generation. The women remain alive for gold.

“Disappointed, but you don’t have time to worry about that,” said Sreejesh Parattu Raveendran, the goalkeeper known as the Wall. “Now we still have a chance to win a medal, and that’s more important for us than crying at this time.”

The golden era started in 1928 when India, which had only been playing international matches for two years, won at the Amsterdam Olympics, scoring 29 goals and giving up none. It won in 1932 and ’36 as well. Dhyan Chand, widely considered the greatest hockey player ever, was part of all three teams.

After World War II, the streak continued, with gold medals in 1948, ’52 and ’56, before India finally lost to Pakistan in 1960. It reclaimed the title in 1964.

But that was the end of the Indian dominance. The country won one more gold medal, in the boycott year of 1980, but has no medals since. India was 12th and last at the London Olympics and eighth four years ago in Rio. In a country where cricket is by far the dominant sport, hockey was becoming more and more of an antiquated curiosity.

But the 2020 India team has been a throwback to its glory days. After a 4-1 record in the group stage, India upended Britain in the quarterfinals, 3-1, to advance to the final four.

The women’s team, without any of the men’s glorious history, has similarly overachieved, shocking Australia in the quarterfinals. It plays in a semifinal of its own against Argentina on Wednesday.

“This will be a very big, big thing in India,” said the women’s team captain, Rani Rampal.

Indeed, the teams are causing a stir back home. The Times of India said the women’s victory over Australia rivaled India’s win over England in cricket at Lord’s in 1983 as the greatest sporting upset in Indian history.

The paper had called the men’s semifinal “an hour of reckoning,” saying that “a win will not just confirm a return to the Games podium, but it will restore belief in the sport.”

Though India lost the game, a bronze and that return to the podium is still in the offing. So too, maybe, is a new day for Indian hockey.

Elaine Thompson-Herah of Jamaica is an Olympic champion — again.

Three days after winning the women’s 100 meters, Thompson-Herah broke clear of the field in the 200 on Tuesday night to win in 21.53 seconds, a national record.

Christine Mboma of Namibia was second, and Gabby Thomas of the United States was third.

Shelly-Ann Fraser-Pryce, who won the silver in the 100, finished in fourth place.

Earlier in the evening, three Americans advanced through the semifinals of the men’s 200 meters — but not without some drama.

Noah Lyles, one of the favorites, slowed as he neared the finish of his heat and was passed by two runners, missing an automatic qualifying spot. He later advanced to the final based on his time. Lyles said he was going with his plan — which apparently meant conserving some energy — but acknowledged that it turned out to be “a little risky.”

The night was capped by Mondo Duplantis of Sweden, who cleared 19 feet 9 inches to win the men’s pole vault. Christopher Nilsen of the U.S. won silver in a final that was absent his American teammate Sam Kendricks, the reigning world champion. Kendricks tested positive for the coronavirus last week and was ruled out of the competition.

Duplantis, 21, grew up in Louisiana but competes for Sweden, his mother’s home country. His first Olympic gold medal assured, he tried to put on a show for the few hundred staff, media and fellow athletes who were in the stadium, but narrowly missed breaking his own world record.

Performing a routine filled with difficulty but performed with grace, Guan Chenchen of China, the youngest competitor on Tuesday, won the gold medal in the balance beam at the Tokyo Games. Simone Biles, in her much-anticipated return, won the bronze behind another Chinese athlete, Tang Xijing, who took the silver.

Guan, who is 16 and in her first Olympics, is a specialist on the balance beam and it showed at these Games. With a routine much more difficult than that of her competitors, she had qualified first for the balance beam final.

On Tuesday, she was the eighth and last gymnast to compete and she nailed split leaps, back handsprings, flips and an aerial before flying into the air for her double pike dismount and landing to applause in the arena. Her score of 14.633 was enough to put her ahead of everyone.

Biles, the face of the sport and of Team U.S.A., returned to competition for the final day of artistic gymnastics after skipping all but one competition because of a mental health issue.

Biles, 24, performed back handsprings, flips, split leaps and a double back flip in the pike position for her dismount. There were a few moments of shakiness, but overall it was a solid routine.

Gone were the twists from her complicated and difficult dismount that was named after her. But she finished her routine with a smile, running to give her coach, Cecile Landi, a hug and then embracing her teammate Sunisa Lee, who did not win a medal.

When her score popped up, Biles shook her head in agreement. It was 14.0, far below her usual score, but the best part of it, according to the look of routine on her face, was that she was done.