OMAHA, Nebraska- Michael Phelps on Wednesday confirmed the events he plans to contest at next month's Beijing Olympics in his bid to beat Mark Spitz's record of seven gold medals at a single Games.

Michael Phelps [File]

With four days remaining at the U.S. swim trials, Phelps' Olympic schedule came into focus when he withdrew from the 200 metre backstroke on Wednesday, leaving him entered in just enough events to attack Spitz's staggering record set at the 1972 Games in Munich.

Phelps celebrated his 23rd birthday during the trials and has already qualified in the 400 individual medley, 200 freestyle, 200 butterfly and the 4x200 freestyle relay.

The six-time Olympic gold medallist has only the 200 individual medley and 100 butterfly left on his trials schedule.

If he qualifies in those two races, his Beijing programme will feature five individual events (200 and 400 individual medley, 200 freestyle, 100 and 200 butterfly) plus all three relays.

There had been wide speculation over which races the versatile and immensely talented Phelps might compete at in Beijing after he was entered in nine events at the U.S. trials.

But over the course of the eight-day competition, he and coach Bob Bowman trimmed his schedule down.

CONTINGENCY PLANS

"There are a lot of reasons," Bowman told reporters when asked why he had entered Phelps in nine events.

"We kind of wanted to keep options open because unforeseen things can happen, Michael pushes, he kicks, stuff can happen.

"We wanted to have some contingency plans but now I don't think that's necessary and we're ready to do our deal."

As well as still needing to finish in the top two in his remaining events, Phelps' selection for the 4x100 freestyle and 4x100 individual medley squads is not automatic.

He staked his claim for a spot in the 4x100 freestyle team on Wednesday after posting a blistering 47.92 seconds to become only the sixth swimmer under the 48-second barrier.

He immediately withdrew from the event feeling he had done enough to secure a place.

"He was trying to break 48 and he did and that sets him up nicely for the relay and hopefully answered some questions for everybody," Bowman said.

"I think Michael should be on the relay, he's put up a time, so there it is."

A victory on Saturday in the 100 butterfly final would also secure Phelps a spot on the medley relay team.