Legendary swimmer Phelps added gold medals 20 and 21 to his incredible Olympic collection as he triumphed in the 200m butterfly and the 4x200m freestyle relay on a very special night for the American.
The 31-year-old powered home to win the 200m butterfly in a time of 1:53.36 to avenge his London defeat to rival Chad le Clos and his night got even better as the USA took gold in the 4x200m freestyle relay.
“That’s a lot of medals,” said Phelps. “It’s just insane. It’s mind-blowing.”
“I wanted that one back. I came into the pool tonight with a mission and the mission was accomplished,” added Phelps.
He cruised to victory in one minute 53.36 seconds as the South African only managed to finish fourth.
Japan’s Masato Sakai and Hungary’s Tamas Kenderesi overtook Le Clos in the final 50 metres to take the silver and bronze medals respectively.