Japan's double Olympic gold medalist Kosuke Kitajima is hoping Michael Phelps will steer clear of breaststroke when he takes up new events.

"Phelps in breaststroke? That would be the last thing I'd like to see," said Kitajima, who won the breaststroke "double-double" in winning the 100m and 200m for a second successive Games.

"I really hope not to see that happening," he added.