Michael Phelps returned to competitive swimming Thursday, posting the fastest time in the 100-meter butterfly prelims at a Grand Prix meet in Mesa, Ariz.

His time of 52.84 seconds was one-tenth of a second faster than Ryan Lochte, who had the second-fastest time. Racing in his first meet since the 2012 London Olympics, Phelps was cheered when he stood on the blocks in the 14th and final heat of the 100 fly.

The top eight advanced to Thursday's finals to be held later that night.

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Phelps, who has a record 22 Olympic medals, holds the world record in the event, 49.82 seconds set in 2009.

He planned to swim the 100 butterfly Thursday after scratching from the 100 freestyle, and 50 freestyle Friday — to see where he stands against elite competition.

"I'm doing this for me," Phelps said Wednesday. "If I don't become as successful as you think I would or should be, that's your own opinion. I enjoy being in the pool and sport of swimming and having fun with what I'm doing."

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