Rio Olympics, Day 1

Katinka Hosszu of Hungary competes on her way to winning gold in the women's 400-meter individual medley. 

Katinka Hosszu celebrates shattering the world record in the women's 400-meter individual medley. Her winning time of 4 minutes, 26.36 seconds knocked two seconds off the previous record. 

Great Britain's Adam Peaty (center) set a new world record in the men's 100-meter breaststroke heats.

Samba dancers pose at the Olympic Aquatics Stadium in Rio.

Judokas Eva Csernoviczki of Hungary (in white) and Otgontsetseg Galbadrakh of Kazakhstan compete in the women's 48-kilogram repechage contests. Galbadrakh ended up winning the bronze medal. 

Yeldos Smetov (left) of Kazakhstan and Diyorbek Urozboev of Uzbekistan compete in the men's 60-kilogram judo competition.

Russia's Beslan Mudranov (white) competes with Kazakhstan's Yeldos Smetov during their gold medal tie in the men's 60-kilogram judo contest, which was won by Mudranov.

The victory ceremony for the men's 60-kilogram judo competition (left to right:) Naohisa Takato of Japan, Beslan Mudranov of Russia, Yeldos Smetov of Kazakhstan and Uzbekistan's Diyorbek Urozboev.

Nozomi Sato of Japan (right) celebrates winning a preliminary tie in the women's epee. 

Serbia's Stefan Bircevic scores a slam dunk against Venezuela during an early round of the men's basketball competition. 

Japanese gymnast Kohei Uchimura loses his grip as he competes on the horizontal bar. 

Azerbaijani gymnast Oleg Stepko competes during qualification on the horizontal bar. 

Members of the South Korean team compete in the men's archery semifinal. The Koreans eventually won gold in the men's team competition. 

Gergo Zalanki of Hungary (right) and Nikola Jaksic of Serbia grapple with each other in an early round of the men's water polo competition. 

Elaheh Ahmadi of Iran takes aim during qualification for the women's 10-meter air rifle competition.

Virginia Thrasher (center) from the United States celebrates after winning the first gold medal of the Rio Games in the 10-meter air rifle competition. 

Cyclists start the men's road race race from Copacabana Beach.