Ian Thorpe will be free to defend his 400 metres freestyle title at the Athens Olympics after his team mate Craig Stevens announced he was pulling out of the event.

In one of the worst-kept secrets in Australian sport, Stevens confirmed on Monday he was giving up his spot to Thorpe so he could concentrate on his other events.

"My decision is to stand aside in the 400 metres," Stevens said in a television interview.

"The decision that's been made has come from the heart."

Thorpe's hopes of swimming the 400 appeared to have sunk when he was disqualified for a false start after slipping off the blocks during last month's Australian trials.

He lost an appeal against his disqualification but was thrown an unexpected lifeline when his friend Stevens, who finished second to Grant Hackett at the trials, said he would consider surrendering his place.

Stevens had also qualified for his specialist event, the 1500 metres, as well as the 4x200 relay, and said he wanted to concentrate on those races.

"I was just hoping to qualify for one event at the Olympic Games so three was something I didn't expect," he said.

"This has been a difficult decision...and there's been a lot of stress and a lot of assumptions.

"But he [Thorpe] said to me, 'it's up to you, it's your choice, I'll support you whatever you do'.

"He's not the sort of person who would put pressure on anyone."

The saga dragged on for almost a month with opinion split on what Stevens should do. Australian Olympic officials consulted their lawyers and Stevens's management team negotiated an exclusive deal to make the announcement live on Australian television.

There was no immediate response from Thorpe after Stevens made his decision public but Australian swimming officials said he is likely to hold a news conference on Tuesday.

Thorpe also qualified for the 100 and 200 as well as the three relays but the 400 is his best event and he is considered a near-certainty to win in Athens.

A national hero after winning three gold medals at the 2000 Sydney Games, Thorpe is the reigning Olympic and world 400 champion and has not been beaten in the event for seven years.