Jamaican sprinter Usain Bolt looks back at his competitors during a 100-meter semifinal on Sunday, August 14. Bolt won the final a short time later, becoming the first man in history to win the 100 meters at three straight Olympic Games. Cameron Spencer/Getty Images

Mexican diver Melany Hernandez competes in the 3-meter springboard event on Friday, August 12. Wong Maye-E/AP

U.S. swimmer Michael Phelps -- the most decorated Olympian of all time -- kisses his gold medal from the 4x200 freestyle on Tuesday, August 9. Phelps finished the Rio Games with five gold medals and one silver. He ends his Olympic career with 23 gold medals and 28 medals overall. GABRIEL BOUYS/AFP/Getty Images

Shaunae Miller of the Bahamas dives over the finish line to win gold in the 400 meters on Monday, August 15. She edged American Allyson Felix by .07 seconds. Matt Slocum/AP

U.S. gymnast Simone Biles, who had already won the individual all-around and the vault, wobbles during the balance beam finals on Monday, August 15. She finished with the bronze. Andrew P. Scott-USA TODAY Sports

Ireland's Fiona Doyle swims the 200-meter breaststroke on Wednesday, August 10. David J. Phillip/AP

U.S. swimmer Simone Manuel cries during the medal ceremony after winning the 100-meter freestyle on Friday, August 12. Manuel is the first African-American woman to win an individual swimming event in the Olympics. Michael Sohn/AP

Weightlifter Sarah Robles won bronze for the United States on Sunday, August 14. It was the United States' first weightlifting medal in 16 years. Laurence Griffiths/Getty Images

Jamaica's Elaine Thompson, right, wins the 100-meter final -- and the title of world's fastest woman -- on Saturday, August 13. FRANCK FIFE/AFP/Getty Images

American cyclist Kristin Armstrong hugs her son, Lucas, after winning the time trial for the third straight Olympics on Wednesday, August 10. Williams won gold at the event a day before turning 43 years old. She was the oldest woman in the field by seven years. AAron Ontiveroz/The Denver Post via Getty Images

U.S. gymnasts Simone Biles, left, and Aly Raisman hug after winning gold and silver in the individual all-around on Thursday, August 11. Mike Blake/REUTERS

British runner Mo Farah crosses the finish line to successfully defend his 10,000-meter title on Saturday, August 13. OLIVIER MORIN/AFP/Getty Images

South Korean fencer Park Sang-young celebrates after he won gold in the individual epee competition on Tuesday, August 9. Richard Heathcote/Getty Images

Triplets Liina Luik, Lily Luik and Leila Luik pose with the Estonian flag after taking part in the marathon on Sunday, August 14. Johannes EISELE-Pool/Getty Images

Cao Yuan and Qin Kai, synchronized divers from China, compete in the 3-meter springboard event on Wednesday, August 10. They won the bronze in a diving pool that had mysteriously turned green. GABRIEL BOUYS/AFP/Getty Images

U.S. field hockey player Melissa Gonzalez falls to the turf during a match against Great Britain on Saturday, August 13. Dario Lopez-Mills/AP

A remote-control car carries the discus during the men's qualifying round on Friday, August 12. FRANCK FIFE/AFP/Getty Images

Brazilian athlete Nubia Soares lands in the sand pit while competing in the triple jump on Saturday, August 13. FRANCK FIFE/AFP/Getty Imagesq

Cameras are set up at the bottom of the swimming pool as women take part in a 50-meter freestyle heat on Friday, August 12. Catching the Olympic moments that TV doesn't FRANCOIS-XAVIER MARIT/AFP/Getty Images

A cell phone falls out of the pocket of French fencer Enzo Lefort as he competes against Germany's Peter Joppich on Sunday, August 7. KIRILL KUDRYAVTSEV/AFP/Getty Images

Larissa Franca, a beach volleyball player from Brazil, is hugged by supporters after a quarterfinal victory on Sunday, August 14. Marcio Jose Sanchez/AP

A fan watches the archery competition in pouring rain on Wednesday, August 10. JEWEL SAMAD/AFP/Getty Imagesq

Australia fans show support for their team during a water polo match against Japan on Wednesday, August 10. Eduardo Verdugo/AP

Ibtihaj Muhammad, the first U.S. Olympian to compete in a hijab, reacts during a sabre fencing semifinal on Saturday, August 13. Her team lost to Russia but still took home the bronze. Tom Pennington/Getty Images

A woman runs by the Puffed Star II sculpture during the Olympic marathon on Sunday, August 14. Matthias Hangst/Getty Images

Ukrainian boxer Tetyana Kob celebrates after she won a flyweight bout on Friday, August 12. Frank Franklin II/AP

A barbell rests on the collarbones of French weightlifter Gaelle Nayo-Ketchanke as she performs a clean-and-jerk lift on Friday, August 12. Mike Groll/AP

American Helena Scutt sails before the start of a 49er FX race on Monday, August 15. Bernat Armangue/AP

Brazilian soccer star Neymar celebrates after a quarterfinal victory over Colombia on Saturday, August 13. He scored the first goal of the match, which ended 2-0. Leo Correa/AP

Athletes race in the semifinals of the 3,000-meter steeplechase on Sunday, August 14. Lucas Oleniuk/Toronto Star/Getty Images

Nigel Paul, a super-heavyweight boxer from Trinidad and Tobago, lies on the canvas after being knocked out by Nigeria's Efe Ajagba on Saturday, August 13. Frank Franklin II/AP

A badminton racket is swung during a doubles match on Saturday, August 13. David Ramos/Getty Images

South Africa's Wayde van Niekerk, left, blew away the competition in the 400 meters on Sunday, August 14. He finished in 43.03 seconds, smashing the world record set by Michael Johnson in 1999. Luca Bruno/AP

South Africa's Chad Le Clos, right, looks over at Michael Phelps during the 200-meter butterfly final on Tuesday, August 9. Phelps' victory avenged one of the few losses of his Olympic career -- a second-place finish to Le Clos in 2012. Adam Pretty/Getty Images

Monica Puig tosses her racket after winning Puerto Rico's first Olympic gold medal on Saturday, August 13. Puig defeated Germany's Angelique Kerber in three sets, becoming the first unseeded player to win gold since women's tennis was reintroduced in 1988. Charles Krupa/AP

U.S. diver Kassidy Cook trains at the Maria Lenk Aquatics Centre on Thursday, August 11. Wong Maye-E/AP

Germany's Christine Wenzel ejects cartridges during skeet qualification on Friday, August 12. Hassan Ammar/AP

New Zealand's Olivia Podmore, left, and Spain's Tania Calvo Barbero fall during a keirin race on Saturday, August 13. Greg Baker/AFP/Getty Images

Israel's Or Sasson offers a handshake to Egypt's Islam El Shehaby after their judo match on Friday, August 12. El Shehaby refused and was later sent home by the Egyptian Olympic Committee. Toshifumi Kitamura/AFP/Getty Images

Ethiopia's Etenesh Diro runs with one bare foot after losing a shoe during the 3,000-meter steeplechase on Saturday, August 13. She still finished the race and advanced to the final. Bernd Thissen/EPA

Thibault Amani Danho, a swimmer from the Ivory Coast, competes in the 100-meter freestyle on Tuesday, August 9. Gabriel Bouys/AFP/Getty Images

American tennis star Serena Williams, the world's top-ranked player and the defending Olympic champion, screams after losing a point to Ukraine's Elina Svitolina on Tuesday, August 9. Svitolina upset Williams to advance to the quarterfinals. Vadim Ghirda/AP