Michael Phelps and Caeleb Dressel of United States celebrate their win the men's 4 x 100m freestyle relay on day 2 of the Rio 2016 Olympic Games on Sunday, August 7.
The United States' Katie Ledecky celebrates after winning the gold medal in the women's 400m freestyle final.
American gymnast Simone Biles leads the field in the women's individual all-around competition at the end of the second day of the Olympics.
Serbia's Novak Djokovic hangs his head after losing a point during his first round singles tennis match against Argentina's Juan Martin Del Potro. The Argentinian beat Djokovic 7-6, 7-6.
Sarah Sjostrom of Sweden celebrates winning gold and setting a new world record in the women's 100m butterfly.