Phelps won't retire after Rio: Lochte

We may not have seen the last of American superstar Michael Phelps at the Olympics.

The 31-year-old is swimming in his fifth Games but long-time teammate Ryan Lochte says he'll go around again at Tokyo in 2020.

"I guarantee he'll be there," Lochte told NBC's Today program when asked if the pair will resume their rivalry in four years.

Phelps retired after the London Games but returned to the pool in 2014.

Interestingly, Lochte made the prediction in 2012 that his countryman would be back.

Phelps would be 35 if he were to make it to Tokyo but is showing no signs of slowing down at Rio.

This week he has already picked another four gold medals in Rio with the 4x100m medley relay still to come.