No swimmer has won seven golds at a single world championship but few would bet against the lanky American becoming the first, and eclipsing Thorpe's record haul of six from Fukuoka in 2001.
Already with high hopes for the Beijing Olympics -- where he aims to beat the six golds he won in Athens in 2004 -- Phelps knows how vital these world championships are in his planning.
"The world championships are very important because they set you up for what happens next year," Phelps recently told reporters.
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"It sends you into the Olympic year feeling confident. For me this is a really big year. What happens there will hopefully set up a good Olympics."
The 21-year-old hip-hop loving American holds the world record for 200m and 400m individual medley and 200m butterfly, is second fastest in history for 100m butterfly and is the reigning world champion for 200m freestyle.
He is also expected to swim in each of the three relays giving him a real shot at all eight events.
Thorpe's surprise retirement last year also boosted the prospects of his fellow Australian Grant Hackett and the Dutchman Pieter van den Hoogenband.
Hackett is chasing an unprecedented fifth straight world title in the 1500m freestyle and defending the 400m and 800m world titles he won in Montreal when Thorpe was also absent.
Hackett's ultimate aim is to win the 1500m in Beijing and become the first male swimmer to win the same event at three Olympics although he fears he may be underdone for Melbourne after recently switching coaches.
"I don't think I've got the absolute best out of myself for these championships... but I'm putting things in place for the bigger picture," he told reporters.
Van den Hoogenband will also be chasing a hat-trick of Olympic titles next year, in the blue-riband 100m freestyle, but has never won a world title and knows this could be his last chance.
The U.S. are strongly favoured to win the lion's share of the men's races but the women's events are far more open with Australia, Germany, the U.S. and possibly China fighting for top honours.
Australia's women dominated the last world championships with Leisel Jones (breaststroke), Libby Lenton (freestyle), Jodie Henry (freestyle) and Jessicah Schipper (butterfly) all winning titles.
The American challenge will rest heavily on the performances of the versatile Natalie Coughlin and the rapidly improving Katie Hoff while Laure Manaudou of France and a new wave of German world record-breakers will lead the European assault.
Manaudou won four individual titles at last year's European championships where Britta Steffen led Germany's women on a sensational world record spree.
Steffen claimed the 100m freestyle record from Libby Lenton and helped her teammates break two relay world records to announce Germany's return as a force in women's swimming.
The performances of the Chinese in Melbourne will also be heavily scrutinised. The Chinese were at the centre of a series of doping scandals in the 1990s but have suffered curiously poor results in recent years, failing to win a single gold medal in the swimming events at the 2005 world championships.
Accused of cheating whenever they win, they also face accusations when they lose amid speculation they were training their best swimmers in isolation and keeping them away from international competition.
Melbourne hosts a week of diving, water polo and synchronised swimming from March 17 before the eight day swimming programme begins on March 25.
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