Coming to a pool at London 2012: Thorpe v Phelps, the showdown

Australian swimming legend inspired to end retirement after five years by prospect of further Olympic glory

It was on a mild, overcast October morning in east London that Ian Thorpe realised where his future lay. Australia's greatest Olympian stood beneath the signature curved roof of the burgeoning aquatic centre, looked into the dry shell of the swimming pool that will host the 2012 Olympic Games and decided beyond doubt that he had to be a part of it.

Yesterday, five years after he last plunged competitively into a pool, Thorpe, still only 28, announced in Sydney that he was coming out of retirement with the aim of making the Australian team for next year's Games. On the other side of the world, in the offices of the London organisers, the news was received almost as gleefully as Down Under. Ian Thorpe versus Michael Phelps at London 2012 is a mouth-watering billing.

It was last autumn that Thorpe was given a tour of the Olympic site by Sebastian Coe. "He was clearly thinking about his future," Coe said yesterday. "I am pretty sure what he saw in the Olympic Park tipped the balance." Thorpe had felt an increasing pull back to the pool over the previous few months and what he saw with Coe that day made his mind up.

"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."

At his peak in the early years of the century, Thorpe was a swimmer without equal, as five Olympic golds, 13 world records and 11 world championship gold medals demonstrates. But having made his debut for Australia aged 14, by the time he pulled out of the 2006 Commonwealth Games the motivation to maintain an arduous training schedule had gone.

"I wanted nothing to do with it," reflected Thorpe yesterday. "I think in the time out from the pool I've just been able to get on with what I wanted, which is a more normal life. But there's just been something that's kind of been nagging and I want to do this. It's probably realistically the last time I'll be able to do it. It was on my bucket list to swim at another Olympics before I was 30 – that, playing James Bond, starting a rock band, being a pilot... and this seemed more realistic."

He will base himself in Abu Dhabi for the required intensive training, coupled to occasional sessions in Europe with Manchester as a possible venue. It was there that he won six golds in the 2002 Commonwealths and it will also be the base for the Australian swim team ahead of next summer's Games.

Thorpe's chances of being among their number will not become clear until next spring. He has signed up to Swimming Australia's drug-testing programme but under the rules of Fina, the sport's governing body, he is not allowed to compete for nine months after registering. That will see him free to swim for a place in his third Games in team trials next March.

His primary aim will be to secure a place in the relay teams – his defining moment came in the 100m relay on a frenzied, raucous night in home waters in 2000 when he left the hugely fancied Americans trailing in the wake of his size 17s – but it seems improbable that he would deny himself the challenge of individual events – if he is up to scratch. And that could bring him face to face with Phelps once again.

Thorpe had the better of the American in their much hyped head-to-head meeting in Athens in 2004, but Phelps took eight golds in Beijing and will be looking to bring his Olympic haul to an incredible 20 in London. He has three years on Thorpe too and few expect the Australian to return to the top of the podium in London. Instead they fear that a hard-earned reputation may end up being tarnished.

"I have had an almost flawless career and I put that at risk," accepted Thorpe. "It would have been a lot easier to 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.

"It's a balancing act where fear and motivation come in – it's a great place to be on that edge."

How the Thorpedo has hit the target

Born 13 October 1982, Sydney

Olympic medals

Sydney 2000: 3 gold, 2 silver, 1 bronze

Athens 2004: 2 gold, 1 silver, 1 bronze

Commonwealth medals

Kuala Lumpur 1998: 4 gold

Manchester 2002: 6 gold

World Championship medals

11 gold, 2 silver, 1 bronze

World records

13 as an individual, 5 in relays