The pair raced at XS nightclub's Encore Pool Party, according to reports. But there is conflicting information about who won the race.
The Mirror reports that Harry won with some help from a friend who held Lochte's legs. The Daily Beast says Lochte won even though the prince had a three-second head start. The website also reports the party was in honor of Lochte's 28th birthday, which was Aug. 3, during the Olympics.