Pieter van den Hoogenband won the men's 100 metres freestyle final at the Athens Olympics on Wednesday to successfully defend the title he won in Sydney.

The flying Dutchman flashed up and down the pool in a slick 48.14 seconds, just three-tenths of a second outside the world record of 47.84 he set at the last Games four years ago.

South African Roland Schoeman finished second in 48.23 to add a silver to the gold he won in the 4x100 freestyle relay.

Australian Ian Thorpe collected bronze in 48.56 to go with the two golds and the one silver he already has in Athens.

Van den Hoogenband won the 100-200 double at Sydney. He finished second to Thorpe in the 200 but showed he is still the king of the two-lap sprint with a perfectly controlled race.

Schoeman had qualified fastest for the final and looked the likely winner after making a lightning start off the blocks and reaching the halfway stage in 22.60, more than half a second under world record pace.

The South African was still ahead approaching the finishing wall but van den Hoogenband, who was fifth after the first 50, timed his run to perfection, edging past him in the final two strokes.

"I'm not sure when I caught him, I was in a kind of trance, in a flow, doing my job and not thinking," said van den Hoogenband.

"I'm so happy, really. I was touching the wall and the camera was zooming in and I'd won. It's great."

Thorpe was striving to become the first swimmer to win the 100-200-400 freestyle treble at the same Olympics but the 100 was always going to be his hardest event.

He scraped into the final as the eighth qualifier so had to swim on the outside lane and looked to have no hope after he was the last to react the gun at the start, leaving the blocks 0.17 slower than Schoeman.

He was sixth when he turned for home, almost a second behind the leader, but began to move through the field on the second lap before edging out South Africa's Ryk Neethling for the bronze.

"I guess I have the set (of medals) now, I didn't think that was going to happen, but I'm really happy with my swims here," said Thorpe.

"It's not about the reaction time, it's about what you do in the first 15 metres."