Ian Thorpe stood atop the victory podium in Barcelona as the first swimmer in history to win the same event at three consecutive world titles.

The triple Olympic champion beat close friend and teammate Grant Hackett for the 400m freestyle gold at Barcelona's Palau Sant Jordi pool in what's become a battle of the two amigos.

The end result in Spain was the same as it had been at the last two world championships in Perth in 1998 and in Fukuoka, Japan, in 2001.

Thorpe has not lost a 400m race in an Olympic-sized pool since 1997.

He clocked 3m42.58s for his ninth world championship gold medal - one more than the record he shared with East German Kornelia Ender.

His time was 2.5s outside the world mark of 3:40.08 he set a year ago at last year's Manchester Commonwealth Games but it was still enough to beat Hackett by about two body lengths.

"I'm pleased with that swim but it's the start of a long meet," Thorpe said after the race.

Hackett clocked 3:45.17 for the silver, well outside his best two years ago in Fukuoka.

His time in Japan - 3:42.51 - would have been enough to better Thorpe.

The 23-year-old was clearly disappointed he let Thorpe get away from him at the 250m mark.

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