Chad Le Clos and Michael Phelps resumed the rivalry that started in London in 2012 for the 200m butterfly semifinal at the Olympic Aquatic Centre in Rio on Monday.
Le Clos snatched gold from Phelps in the 200m Butterfly final in the 2012 games. However, Phelps received his redemption Tuesday in Rio. He won the 200m butterfly as Le Clos finished fourth. Here's what you need to know about their rivalry. (Getty)