The big Australian has a new coach, a new programme and a fierce new rival trying to take over his mantle as the world's best swimmer.
Thorpe has hardly missed a beat since he burst on to the international stage in 1997 as a 14-year-old but all the signs suggest the bubble could burst in Barcelona, where swimming gets under way on July 13.
He is still only 20 but has not broken a world record in almost a year and his chances of bettering his incredible haul of six gold medals at the last world championships are sinking by the day.
The Australian men's relay team, which won three gold medals in Japan two years ago, is nowhere near as strong this time after the withdrawal of Michael Klim and is expected to win just one gold medal this time.
Thorpe is entered in four individual events but is not sure to win them all and could finish with as few as two golds.
He won the 200 and 400 metres freestyle events last time and will be heavily favoured to win them both again. He is also a strong contender, but no certainty, in the 100 sprint after finishing fourth in that event last time.
PHELPS THREAT
But Thorpe has dropped the 800, which he sensationally won in Fukuoka with a world record time, after it was left off the schedule for next year's Athens Olympics, and replaced it with the 200 individual medley (IM), a new event he is still coming to grips with.
Thorpe is making steady progress but not quickly enough to worry Michael Phelps, the United States teenager who recently smashed the 200 IM world record and is now poised to challenge Thorpe as the world's best all-round swimmer.
Phelps also holds the 400 IM and the 200 butterfly world records and with the backing of a powerful relay squad, he is already being described as America's answer to Thorpe, not that the Australian
Thorpe has already conceded that he does not expect to better his collection from the last world championships, but the smell of chlorine is still in his nostrils.
With two gold medals from the 1998 world championship safely tucked in his trophy cabinet, Thorpe needs just one more to surpass East German Kornelia Ender's record total of eight, which they currently share.
Should Thorpe win the 400, his signature event, he will become the first male swimmer to win the same individual event at three world championships.
Thorpe, whose staggering list of achievements also include three Olympic gold medals and 10 Commonwealth titles, says he is thriving on the challenge Barcelona presents.
The shy Sydneysider was an unrivalled success at last year's Commonwealth Games in Manchester, England and the Pan Pacific championships in Yokohama, before boredom began to set in.
He took a month off to travel around Europe and Asia then almost threw in his goggles last year because he was sick of the grind of training.
SEEKING BULLSEYE
But Thorpe rediscovered his enthusiasm after dumping his long-term coach Doug Frost to train under Tracey Menzies, a Sydney art teacher who had worked as Frost's assistant.
When Thorpe, a serial world record breaker, failed to set a world record at this year's Australian national championships, there were concerns that his decision to part with Frost could jeopardise his career.
But Thorpe and Menzies say they are working on new training techniques they hope will help to improve his speed and increase his chances of more Olympic gold in Athens next year.
"I guess I've fired the arrows, I'm just waiting for the bullseye now," Thorpe said.
"I'm happy with the way things are coming along at this stage. Things can change but I'm positive with where I'm at, at the moment, and I'm looking forward to Barcelona."