Phelps captured his 21st Olympic gold medal in dramatic fashion in Rio, sealing victory with a kiss from baby son Boomer, before adding
a staggering 21st before the night was over.
Phelps has three gold medals in Rio - to date - with the chance to add three more in the remaining days of competition.
Phelps' fiance, former Miss California Nicole Johnson, has been pool-side throughout the swimming in Rio, with three-month old baby Boomer stealing the limelight.
If he does indeed retire following the Rio Games, a big THANK YOU to the greatest ever Olympian.