PHOENIX (REUTERS) - Michael Phelps made an ominous start in his comeback to competitive swimming on Thursday, setting the fastest time in the 100 metres butterfly heats at a USA Swimming Grand Prix meet in suburban Phoenix.
Racing for the first time since he retired in a blaze of glory after the 2012 London Olympics with a staggering career total of 18 gold medals, a relaxed Phelps cruised to victory in 52.84 seconds.
His time was well outside the world record of 49.82 seconds he set at the 2009 world championships but still safely under the qualifying time for this year's US national championships, which double as the selection event for next year's world titles in Russia.
Phelps will swim again later on Thursday in the 100m butterfly finals and was also entered for Friday's 50m freestyle heats.
Although the 28-year-old American still holds the world record in three individual events, none of his past times count for future events because they were all recorded before the qualifying period began in June 2013.
Phelps and his coach Bob Bowman were both reluctant to talk about their long term goals when they appeared at a packed news conference on the eve of his comeback but they did not rule out the possibility of competing at the 2016 Rio Olympics.
Unshaven and still three kilograms over his ideal racing weight, Phelps had planned to swim in three events at his comeback meet but ditched the 100m freestyle to focus on the 100m butterfly and Friday's 50m freestyle.
Tickets for the event sold out within hours after Phelps confirmed he was making his comeback and were selling for more than five times their face value on the secondary market.
More than 100 media - a 500 per cent increase on last year's meet - descended on the Skyline Aquatic Center to see him take his first plunge back into the water.
Even before his race, the crowd at the warm-up was five deep with people trying to snap a picture of him practicing with his kickboard.
When he climbed on to the blocks, the crowd roared and he made a clean getaway.
Phelps reached the turn in second place then pulled away from his rivals on the second lap, rolling his powerful shoulders over and over to reach the wall first and book his place in Thursday night's final.