Michael Phelps won the men's 100m butterfly here Friday, claiming the 17th gold medal and 21st total medal of his Olympic career with a stirring last-lap surge.
Phelps, seventh at the turn, won in 51.21sec to claim his third straight Olympic gold in the event.
South Arican Chad Le Clos and Russian Evgeny Korotyshkin shared silver, both clocking 51.44.
Serbian Milorad Cavic, famously beaten by Phelps by one one-hundredth of a second in Beijing four years ago, went out hard in an effort to turn the tables.
He led at the turn but faded to finish equal fourth with Germany's Steffen Deibler in 51.81sec.