Phelps, 23, says he is stronger both physically and mentally as he prepares for another assault on Mark Spitz's record of seven gold medals in one Olympic. In Athens, four years ago, he came away with an impressive six gold and two bronze, but insists those who say eight golds are impossible -- including now retired Aussie great Ian Thorpe -- are wrong.

Phelps, now the world record-holder in four of his five individual events, captured seven titles at last year's world championships, whetting appetites for a dazzling display in the Water Cube -- the futuristic National Aquatic Centre that is a showpiece of the Beijing Games.

"I think if anyone in the world can possibly do it, it's Michael," said Australian swim coach Alan Thompson. "I think it will be a great story over the nine days of competition. There will be a lot of people watching hoping to see history."

The United States have won a staggering 458 medals -- including 202 gold -- in the history of Olympic swimming. Australia is the only other country in triple figures with 157, including 52 gold.

The two will again dominate, but both face an increasing challenge from a fleet of superb swimmers from around the globe.

France boast of 100m freestyle world record-holder Alain Bernard. Japan's Kosuke Kitajima is intent on defending his two breaststroke titles from Athens. Italy brings freestyle swimmer Federica Pellegrini, while US-based Zimbabwean Kirsty Coventry returns to defend her 200m backstroke crown.

"There's a large number of nations that are going to take the medals this time," Thompson predicted. "I'm sure this will be the most spread of medals we've ever seen at the Olympic Games. Great Britain were fourth at the World Championships in the points score. A lot of small European nations will come along and take some.

"I think the French have been big improvers after their trials -- they're probably well and truly the favourites in the men's 4x100 freestyle relay."

All will have to adjust to the unfamiliar format of morning finals and evening heats at the Water Cube, where the 32 swimming events, diving and synchronised swimming will be held.

Sheathed in a Teflon-like outer membrane that resembles water bubbles, the building is home to a pool that is drawing raves from Olympic swimmers. The depth of the pool and state-of-the-art gutters makes for less wave action and potentially faster times.

The high-tech facility is a fitting backdrop for a revolutionary piece of swimming technology -- Speedo's LZR Racer swimsuit.

Swimmers wearing the form-fitting bodysuit have set nearly 50 world records since it was released in February.

Belief that the LZR offers a clear competitive edge has sparked a stream of defections from other suppliers by swimming medal hopefuls and a race by rival manufacturers to come up with a similar product.

The technical advances combined with the determination of swimmers to make the most of the Olympic moment promise some spectacular performances.

"It's going to take fastest times we've ever seen to make the semis, faster times to make the finals," Thompson said. "I think we're in for a pretty good meet."

Phelps isn't the only swimmer chasing history. Australian Grant Hackett and Dutchman Pieter van den Hoogenband arrive in Beijing with a chance to do what no male swimmer has done before -- win the same individual event for a third time.

Van den Hoogenband will be aiming for a third straight gold in the prestigious 100m freestyle. His rivals will include Bernard, who twice lowered the 100m free world record at the European Championships in March and two-time World Champion Filippo Magnini of Italy.

Hackett will try to accomplish the feat in the 1,500m freestyle, in which he has held the world record of 14min 34.56sec since 2001.

The world has gained on Hackett, and for the first time all eight swimmers in the Beijing 1500m final are likely to swim under 15 minutes.