Olympic legend Michael Phelps on Tuesday clinched his 21 gold medal after winning individual and team titles on Day 4 of the Games.

The American crushed his competition, including long-time rival Chad le Clos, in the 200m butterfly. He also powered Team USA to a win the 4x200m freestyle relay.

The 31-year-old completed the race in one minute 53.36 seconds. The South African, who beat Phelps in London 2012, could manage only a fourth place finish.

"I wanted that one back. I came into the pool tonight with a mission and the mission was accomplished," said Phelps.

The duo is bound to collide again later this week in the 100m butterfly. Phelps is also due to compete in the 4x100m medley relay and 200m individual medley.

It was a well-established fact that Phelps came out of retirement to avenge his London 2012 defeat at the hands of Clos.

The Baltimore Bullet is the most decorated Olympian in history.  His medals tally is more than twice as that of next athlete on the list.

Little over an hour after his triumph, Phelps teamed up with Conor Dwyer, Francis Haas and Ryan Lochte to defend USA’s relay gold.