Phelps' Bad Back Setback

Swimmer and Olympic gold medalist Michael Phelps pulled out of the 400 meter individual medley at the short course world swimming championships Friday due to a sore back.

Phelps' withdrawal ends his goal to emulate his performance at the Athens Olympics, where he won six gold metals.

Phelps, 19, won the 200 freestyle Thursday but then told reporters he felt tired and sore.

"I was really hurting pretty bad the final 75 meters, I was definitely in pain," said Phelps, after his Thursday race. "My body has been beaten up pretty good in the last three months."

Phelps will receive medical treatment and could still swim in the 4x200 freestyle relay, the final event of the competition, according to Reuters.

Phelps admitted to being far from his best coming into the championships, possibly due to distraction from his numerous sponsor commitments, endorsements and promotional appearances since his return from Athens six weeks ago, reported Reuters.

With Phelps out of competition, Australia's Adam Lucas was the top qualifier in the 400m individual medley, completing the race in four minutes, 11.66 seconds.