By Andrew Fraser
BBC Sport in Athens
It took Michael Phelps exactly four minutes and 8.26 seconds to show the world how serious he is about his Olympic mission.
With 12,000 of us at the Olympic Aquatic Centre wondering just how far he can go as he tries to eclipse the feats of Mark Spitz, Phelps calmly ticked the first box.
The 19-year-old American had always been expected to win the 400m individual medley, but his world record set the tone for an electric night in the pool.
"This is the biggest of the big and I was more ready than I have ever been," a shell-shocked Phelps said at his post-race news conference.
"I've thought about this every day for my entire swimming career. There's nothing better in the world.
"This race was for the whole of the US team. It's really going to start something for the rest of the meet."
Not if the Aussies have their way, it won't.
As the cheers for the first American gold medal of the Games died down, the man Phelps is trying to replace as the biggest fish in the Olympic pond responded.
It was not the imperious Ian Thorpe of Sydney four years ago, the Thorpedo just edging out team-mate Grant Hackett to retain his 400m freestyle title.
But his victory set the scene perfectly for the 200m freestyle final on Monday night when Thorpe will go head-to-head with Phelps.
Thorpe dedicated his win to team-mate Craig Stevens, who gave up his place in the event after Thorpe was disqualified at the Australian trials for falling in the pool before the start.
He then surprised the media by failing to name Phelps among his main threats for 200m freestyle gold.
But Thorpe made a point of playing down the rivalry between the pair.
SWIMMING MEDALS TABLE
Gold Silver Bronze
Australia: 2 1 0
USA: 1 3 1
Ukraine: 1 0 0
Argentina: 0 0 1
Holland: 0 0 1
Hungary: 0 0 1
"I like Michael. We are friends and I think he's one of the most talented athletes we have seen," he said.
"I'm very supportive of his quest to achieve seven gold medals (Phelps may not be selected for the medley relay).
"For a long time I've said that when people concentrate on that number, there is a risk that anything short of it is deemed a failure.
"I don't want to see that happen to any swimmer.
"Michael has a tremendous future in this sport and we should be judging him on his own performances rather than trying to compare him to anyone else."
While the Americans picked up five medals to Australia's three, their rivals had the last word by ending the evening with a world record of their own.
The expected duel with the US quartet in the women's 4x100m freestyle relay lived up to its billing, with the Australians edging home for the team's second gold.
Phelps revealed that he listened to the tune Till I Collapse, by rapper Eminem, as he walked out into the arena.
It is the same pre-race routine he used at last year's world championships, where he won six gold medals.
And if his storming start is anything to go by, he will give up his last drop of energy as he looks to seal his own special place in Olympic history.