Ian Thorpe is expected to accept an offer to defend his Olympic 400 metres freestyle title at Athens after Craig Stevens withdrew from the event on Monday night.

Stevens told Channel Seven's Today Tonight program he had decided not to swim the event.

He confirmed Australian sport's worst-kept secret on Monday night, ending weeks of speculation after Thorpe was disqualified from his pet event for a false start at the national trials in Sydney last month.

"The decision I've made is to stand aside in the 400 freestyle in the hope that I'll get to see Ian swim that race in the final on day one of the Olympic Games and to also put all my focus on two other events - the 4x200m freestyle relay and the 1,500 metres freestyle," Stevens said.

Thorpe - the 400 metres freestyle world champion, world record-holder and unbeaten in the event for seven years - will attend a press conference at 12pm (AEST) on Tuesday.

He is expected to talk with his coach Tracey Menzies and Australian head coach Leigh Nugent before announcing he'll take Stevens' spot and attempt to defend his only individual Olympic gold medal in August.

Thorpe reportedly made contact with Stevens on Monday night to confirm the 23-year-old wasn't pushed into making the decision.

Thorpe, 21, had said he would swim the 400m only if satisfied Stevens had made the decision to benefit his preparation for the 1,500m freestyle.

Stevens, 23, said although he listened to plenty of advice, the decision was ultimately his and he knew he'd made the right choice.

"In the end, it's all just been based on me," Stevens said, admitting the pressure had led him to sleeping pills.

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