Margaret Hoelzer set a world record in the 200 metres backstroke in the first final of day seven of the US Olympic Trials in Omaha, Nebraska on Sunday morning.

The 25-year-old clocked two minutes 6.09 seconds to better Zimbabwean Kirsty Coventry's mark of 2min 6.39sec set in February.

Elizabeth Beisel, 15, was second in 2:06.92 to qualify for the Beijing Games next month.

Michael Phelps edged out world record holder Ian Crocker to win the men's 100m butterfly.

Phelps, expected to aim for a record eight golds in Beijing, clocked 50.89sec, 0.73sec ahead of Crocker, but 0.49sec outside the latter's world record, set at the 2005 World Championships in Montreal.

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