SYDNEY -- Five-time Olympic gold medalist Ian Thorpe said he has plenty to lose by ending more than four years of retirement in a bid to compete at next year's London Games.
"I have had an almost flawless career, and I put that at risk," Thorpe said Wednesday at a news conference to announce his comeback.
"It would have been a lot easier and sit on that and not do a thing. But there are still things in swimming that I haven't done, that I would like to achieve," he said. "It's a balancing act where fear and motivation come in -- it's a great place to be on that edge."
Thorpe, 28, confirmed he has registered for drug testing in order to be eligible to compete in the Australian Olympic selection trials in March 2012.
He will spend most of his training in the lead-up to the trials in Abu Dhabi and Europe, concentrating on the 100- and 200-meter freestyles with an eye to competing in the relay events at London.
"It hasn't been something that I have taken lightly in making a decision in returning to competitive swimming, but I actually made a decision in September," he said.
Thorpe retired in November 2006 after setting 13 world records and winning 11 world championship golds. He won the 200 and 400 free at the 2004 Athens Olympics in his last major international meet.
"When I made that decision [to return to swimming] I ... was not able to say anything because I was commentating for the BBC, so it was sitting in my gut for a while," he said.
"I was then taken to see the swimming venue for the London Games. It was an extraordinary venue, and I could actually taste it. I haven't felt like swimming like that for a very long time," he said.
Thorpe submitted a FINA Return to Competition Form to Swimming Australia, which had been sent to the international governing body for processing. Once the form is processed by FINA, normally in a few days, he will have to wait nine months before he can compete domestically and internationally at a FINA-recognized competition
Swimming Australia head coach Leigh Nugent said Thursday that FINA had confirmed Thorpe can begin swimming competitively on Nov. 2 after he registered with international drug-testing authorities.
"This is fantastic news for our sport and the Australian swim team, and I'm particularly excited for Ian that he's decided to return to the pool," Nugent said.
Thorpe burst onto the international stage as a teenager in 1999 and won three gold medals -- all in world-record times -- and two silver medals at the 2000 Sydney Olympics.
The man dubbed "Thorpedo" was the world's highest-profile swimmer until Michael Phelps came onto the scene and had a list of lucrative endorsement deals. But Thorpe admitted last year that he'd had financial problems after his personal savings were affected by the global economic crisis.
He said Wednesday he was not motivated by money in his comeback, only performance.
"I didn't get back in the pool to get fit, I didn't get back in the pool for any other reason than to be back ... at being able to compete at an elite level," he said.
"When I initiated the training, I promised myself first to train for three days, then I said if I got through that I would give myself three weeks, and if I got through three weeks I would get through three months, then make a decision about this," he said.
Nugent also recently confirmed he'd been in regular contact, offering advice on how to regain fitness in the pool.
"I never thought I would be swimming in a competitive way again, but I'm glad that I am," Thorpe said. "I've spent four years away from the pool and I needed those four years."
On Thursday, Thorpe completed his first official training session of his comeback in a private lane at the Ian Thorpe Aquatic Centre.
Hitting the water at 6:30 a.m., Thorpe completed a two-hour session with Nugent in what Thorpe later called an "average hit-out."
"I didn't feel that much different than I did yesterday, except I knew I'd have everyone here watching this morning so I had to make sure I was working my turns a little bit better and keeping myself on my toes," said Thorpe.