Katie Ledecky signs autograph for Michael Phelps

Once upon a time, Michael Phelps signed an autograph for Katie Ledecky.

Ledecky has now returned the favor after the two dominated the swimming competition in Rio.

Phelps and Ledecky combined to win 11 medals at these Olympic Games, nine of them gold.

They'll both probably be signing tons of autographs when they get back to the United States.