London, England (Sports Network) - Michael Phelps will retire on top.
Phelps won his 18th career Olympic gold medal Saturday night, and 22nd overall as part of the heavily-favored U.S. men's 400-meter medley relay team.
Both medal counts extend his records. Phelps swears London will be his fourth and final Olympics. He won the race with Matthew Grevers, Brendan Hansen and Nathan Adrian.