When Michael Phelps decided to come out of retirement, he circled one race in particular on the Olympic schedule.

The 200-meter butterfly.

At the London Games, in what was supposed to be his Olympic farewell, Phelps was leading as he came to the wall in the stroke he does better than anyone.

But he mistimed the finish, glided a little too long, and was edged by Chad le Clos.

That result has irked Phelps ever since.

On Tuesday night, he’ll get a chance to make amends against the South African.

Call it the Rematch in Rio.

“Should be a fun race,” Phelps said.

Le Clos knows he’ll be facing the most decorated athlete in Olympic history, a highly motivated rival still at the top of his game as he showed in leading the United States to a stirring victory in the 4×100 freestyle relay.

But Le Clos isn’t backing down.

“May the best man win,” he said. “I’ll race my heart out.”

A pair of Hungarians could also be part of the mix. Tamas Kenderesi posted the fastest time in the semifinals, edging out Phelps, and five-time Olympic medalist Laszlo Cseh put up the third-fastest time. Le Clos was fourth, not bad considering it was the back end of a grueling double, coming less than an hour after he claimed silver in the 200 freestyle.

“Of course there’s a huge rivalry between Michael and myself,” Le Clos said. “I race to win and I want to beat Michael.”