James Gibson won Great Britain's first gold medal of the 2003 World Swimming Championships with victory in the 50 metres breaststroke on Wednesday.
Gibson, who won bronze in the 100m event on Monday, became the first Briton to win gold at the championships since David Wilkie in 1975.
Gibson recorded a time of 27.56 seconds as he beat defending champion and world record holder Oleg Lisogor of Ukraine into second, with Hungarian Mihaly Flaskay in third.
"I feel fantastic," said Gibson. "I had a good start - they had to come out to beat me today but I made sure that in my head they wouldn't do it.
"This wouldn't have been possible without the support of my friends, family and supporters.
"This has been a team effort. I was the most chilled-out man out there - I think that was the key."
There was another good British performance in the men's 200m breaststroke, with Ian Edmond beating his own British record as he reached the final.
Gibson shows off his gold medal
There was a thrilling end to the day as Australia fought back to beat bitter rivals America in the 4x200m relay.
The US were given a fine start by 18-year-old sensation Michael Phelps and led by 10 metres after the second leg.
But Australia hauled them back and, when Ian Thorpe started the final leg level with his American opponent, there was only ever going to be one winner.
There was better news for Phelps in the 200m butterfly final.
He won by two-tenths of a second from Japanese star Takashi Yamamoto and fellow American Thomas Malchow.
In the women's 200m freestyle final, Alena Popchanka of Belarus produced a storming finish to edge out veteran Slovakian Martina Moravcova.