INDIANAPOLIS, (Reuters) – Michael Phelps broke the  100 metres butterfly world record by clocking 50.22 seconds at  the U.S. National championships yesterday.

Gold medallist at the Beijing Olympics, Phelps trimmed .18  seconds off the old mark of 50.40 ending American compatriot Ian  Crocker’s six-year hold on the record.

Phelps previously held the 100 fly mark for one day having  broken the record in the semi-finals of the 2003 world  championships in Barcelona.

Crocker took the record with victory in the final the next  day and has lowered it twice since — the last time at the  worlds in 2005.

Phelps now holds five individual world records — 400 and  200 individual medley, 200 and 100 butterfly and 200 freestyle.