Michael Phelps swam the 200m butterfly as his only event in his Olympic debut at the Sydney Games in 2000. He won gold in the event in 2004 and 2008, but fell short in 2012. Le Clos took gold over Phelps by 0.05 seconds.
In Monday night’s semifinals, Phelps and le Clos did head-to-head battle in the same heat, racing in lanes 3 and 5.
Hungary’s Tamas Kenderesi won the heat in one minute, 53.96 seconds. Phelps clocked 1:54.12 to le Clos’ 1:55.19 seconds. Both move onto Tuesday’s final, which will be Phelps' fifth.
About an hour earlier in the session, le Clos earned a silver medal in the 200m freestyle.
“I’m finishing well," Phelps told media after the race. "I need to probably work on some momentum going in and out of turns. But as a whole I didn’t chop any walls tonight. I thought my underwaters were better than this morning. I feel a lot better than I did this morning.”
Joining the juggernauts is Hungary’s Laszlo Cseh, the 2015 world champion in the event. His 1:54.12 was good enough to advance in third place.
The U.S.’ Tom Shields finished 20th in the preliminary heats and did not advance to the semifinals.