Ian Crocker swims to a 100m butterfly world record in Long Beach on Tuesday. (Reuters)

Long Beach: Ian Crocker broke his own 100m butterfly world record here, clocking 50.76 seconds, to hold off Michael Phelps at the US Olympic swimming trials.

Crocker bettered the 50.98 he set in winning the event at the world championships in Barcelona a year ago.

At the world meet, Phelps had set a world record in the semi-finals before Crocker claimed the record and the title in the final. Once again, Crocker had just a little too much for the 19-year-old from Baltimore.

But Phelps’ second-place finish in 51.15 was still enough to earn him the passport to swim six individual events at the Athens Games next month.

“When you’re racing against Michael, you just have to take it one stroke at a time,” said Crocker, who is also qualified to swim the 100 freestyle in Athens.

“I knew it was going to take a world record to win that race, and Ian was too far ahead of me,” Phelps said.