Michael Phelps came up with the perfect goodbye — if it was one.
He won the 23rd Olympic gold medal of his career on Saturday night by swimming his best stroke, the butterfly, in the 4x100 medley.
If he retires, as he insists he will despite joshing about it from teammate Ryan Murphy in a post-swim interview, he leaves behind a singular legacy.
It is, simply, this: Phelps has won 23 Olympic gold medals; the next closest athlete has 18 total medals.
He did it across four Olympics, highlighted by his perfect eight in a row in 2008. He competed as a precocious 15-year-old in the 2000 Sydney Games, but won all his his medals in Athens, Beijing, London and now Rio.
Whether he competes in Tokyo in 2020 or not, he'll leave Brazil with five gold medals and a silver, giving him 28 Olympic medals in all. That mark could stand for a long time.
His final race began with a dramatic moment, when Murphy led off the relay with a world-record time of 1 minute, 18.90 seconds on the backstroke leg.
Britain's own world record holder, Adam Peaty overtook Cody Miller on the breaststroke leg.
But Phelps was up next, and in his final swim he did what he had done for the U.S. so many times before, and beat everyone else in the pool. He handed over the lead to Nathan Adrian and, when Adrian was done, the USA had an Olympic record of 3:27.95 as a going-away present for Phelps.
If this is actually his farewell.
"No, it is, it is," Phelps said. "You could tell, I was much more emotional after the relays this time."