Michael Phelps issued a statement of intent after his fifth individual victory in the US Olympic Trials in Omaha, Nebraska.

The 23-year-old powered to 100-metres butterfly glory ahead of world record holder Ian Crocker and is expected to embark on another gruelling programme at the Games in Beijing next month in an effort to eclipse Mark Spitz's 36-year-old record of seven gold medals.

"I'm only halfway done," said Phelps, who won six gold and two bronze medals in Athens four years ago.

"It's a week of competition that's come to a close, and now we have a month to prepare for the Olympics.

"Hopefully we can come back in another month and prove the US is the best team in the world."

Phelps, the defending Olympic and world champion in the 100 butterfly, clocked 50.89 seconds, 0.73secs ahead of Crocker, but 0.49secs outside the latter's world record, set at the 2005 world championships in Montreal.

Phelps won the men's 400m individual medley, 200m freestyle, 200m butterfly and 200m IM earlier this week - setting world records in each of the multi-stroke events. The relay events would complete his epic workload in China.