Rio de Janeiro Aug 6 (IANS): Australian swimming legend Ian Thorpe has backed his former rival Michael Phelps to become the first swimmer to win the same event at four consecutive Olympics in Rio.

Phelps will be aiming to grab his place in history in both the 100m butterfly and 200m individual medley during the August 5-21 Games, reports Xinhua.

If he succeeds, he will join Al Oerter (discuss) and Carl Lewis (long jump) as the only athletes to have achieved the feat.

"Wishing 'my boy' the best for his 5th Olympics. I can't wait to see him make history again at these Games. Watch out for him in the 100 Fly and 200 IM! He can and will become the first athlete in swimming to win the same event in 4 consecutive Olympics," Thorpe wrote on Instagram on Friday. 

Phelps, who will be competing at his fifth Games, is the most decorated Olympian of all time, having won 22 medals - 18 of them gold.

In addition to the 100m butterfly and 200m individual medley, the 31-year-old will compete in the 200m butterfly in Rio. He is also expected to be a part of the USA relay team.

Thorpe is Australia's most successful Olympian with five gold medals, including three at the Sydney 2000 Games.