Ian Thorpe's bid to swim at his third Olympics faces its moment of truth at the Australian selection trials starting in Adelaide Thursday. The attempt by Australia's most successful Olympian to compete in July's London Games has dominated the lead-up to the national trials, where world champion James Magnussen is looking to attack the 100m freestyle world record. Thorpe, 29, who won a total of five golds at the Sydney and Athens Olympics, has struggled to reproduce anywhere near the times he swam in his prime with a string of disappointing results since his comeback in Singapore in November. But coaches and rival swimmers have warned against writing off the ‘Thorpedo', who ruled the pool from 1998 to 2004, taking nine Olympic medals and 11 world titles, while setting 13 long course world records. Thorpe admits he does not have high expectations in the 100m and 200m freestyle events at the trials after modest results in lead-up events so far. “The most realistic outcome of this is that I will most likely fail,” he said. Australia's selection policy is to pick the top two from each event at the trials for the Olympic team, leaving Thorpe no further opportunities afterwards. But Grant Hackett, one of his main rivals in a golden era of Australian swimming, was not prepared to discount Thorpe's chances. “Ian has done so much for the sport of swimming in this country,” Hackett said. “He deserves our support and best wishes. He knows he is up against it, but he knows how to swim well when it counts.”