Rio Highlights: Usain Bolt Defends Crown; S. African Sets World 400 Record

Jamaica's Usain Bolt retained his title as the "world's fastest man," accelerating past all challengers to win the men's 100 meters for an unprecedented third time on Sunday night in Rio.

In trademark fashion, Bolt unpacked his lanky 6-foot-5 frame and separated himself from the tightly bunched field to win by a comfortable margin in a time of 9.81. His closest competitor, Justin Gatlin, hung with Bolt for the first half of the race, but couldn't match Bolt down the stretch. Gatlin took the silver in 9.89.

"All I had to do was stay cool and get back into it at 60 meters," Bolt told NBC after the race.

The charismatic Bolt is attempting to do exactly what he did in 2008 and 2012 — win the 100, the 200 and the 4x100 relay.

With one win in his pocket at Rio, Bolt now has seven Olympic golds in his career. If he wins the next two events this week, he'll match American sprinter and long jumper Carl Lewis with nine, the most ever won by a track and field athlete.

In fact, the only athlete in Olympic history to win more than nine golds is Michael Phelps, who won his 23rd on Saturday night in what he said was his last Olympic race.

The men's 100 meters was one of the most widely anticipated events in the games. Yet when Bolt stepped onto the track just before his race, he looked up at the scoreboard and gasped — visibly moved by the world record time from the just completed men's 400-meter race.

That record belonged to South African Wayde van Niekirk, who shocked the entire stadium, not just Bolt, with a scorching 43.03, smashing the mark of 43.18 set in 1999 by American Michael Johnson.

His record was all the more impressive because he had the disadvantage of running the one-lap race in lane eight. Due to the staggered lanes, van Niekirk could not see the other seven runners behind him, which makes it harder to judge the pace of competitors.

"I was running blind all the way," Van Niekerk said. "I thought someone was going to catch me — what's going on, what's going on, and it gave me motivation to keep on pushing."

But he rocketed out of the blocks and led the entire way, finishing far ahead of Grenada's Kiranai James, the 2012 winner in the event, and LeShawn Merritt, the 2008 winner.

After Bolt won his race, he found van Niekirk and the two champions embraced.

Outside the stadium, the women ran the marathon on the streets of Rio on a warm, humid morning.

Kenyan women won silver in the marathon at the past three Olympic Games, but had never won gold. That drought ended as Jemima Sumgong passed Bahrain's Eunice Kirwa with two miles to go and never looked back on a warm, sticky Sunday.

For all the success of Kenyan distance runners, men and women, Olympic gold in marathons has proved elusive. Only one Kenyan man has won the event.

Sumgong triumphed in 2:24:04, nine seconds ahead of Kirwa. All three Americans in the race finished in the top 10, but none made it to the medal podium. The race began and ended in Rio's Sambodromo, the parade ground where the city's Carnival takes place every year.

You can see our full marathon story here.

There was plenty of action elsewhere on Sunday. Here are the highlights:

Simone Biles wins on the vault

Biles, who already won golds in the individual all-around and as part of the U.S. team last week, kept her record perfect in Rio as she won the vault on Sunday.

In the vault final, all eight competitors have two vaults and their scores are averaged. Biles delivered two monster scores — 16.033 and 15.900 — on two extremely difficult vaults, one called the Amanar and the other known as a Cheng. She nailed them both.

Biles became the first American woman to win three golds in one Olympics and she's still got a shot at a couple more, on the balance beam and on the floor. She won't be competing in the finals of the uneven bars.

Our full gymnastics story is here.

Britain's Justin Rose wins in golf

Britain's Justin Rose and Sweden's Henrik Stenson teed off on the 72nd hole of the Olympic golf tournament tied, with a playoff looking likely.

Rose shot a birdie-four and finished at 16 under par for the tournament, while Stenson three-putted for a bogie six. Rose won by two strokes in the first Olympic golf tournament since the 1904 Games in St. Louis.

Afterward, Rose said the gold medal "sits alongside the [U.S.] Open trophy, for sure."

Matt Kuchar of the U.S. shot a 63 on Sunday — eight under par for the best score of the day — to pass several rivals and claim the bronze on the Olympic Golf Course, which was built for the Summer Olympics. The women's tournament comes this week, and after the Olympics are over, this will become a public course.

Our full golf story is here.

U.S. men's basketball wins another close one

For a team that's won 50 straight games in international play, the American men are looking rather vulnerable.

The U.S. held off France 100-97 on Sunday on the strength of Klay Thompson's 30 points, most of them coming on seven three-pointers. France's Tony Parker, the long-time star of the San Antonio Spurs, didn't play due to a toe injury.

This was the third consecutive tight game for the U.S., which beat Serbia by three, 94-91, and topped Australia by 10, 98-88, though that game was close until the very end.

The U.S. is now 5-0 in Rio and advances to the quarterfinals on Wednesday. While the Americans have been able to put up points, their defense has not been able to shut down opponents, as many had expected under coach Mike Krzyzewski.

"This isn't a tournament that we're going to just dominate," U.S. guard Paul George said. "There's talent around this world and they're showcasing it. For us, it's just figuring out how we're going to win. We're having spurts of dominating, but we're just not finding ways to put a full 40 minutes together."