Britain's Adam Peaty broke the 50m breaststroke world record in the semi-finals at the European Championships.
The 19-year-old, who has already won two golds in Berlin, won his semi-final in a time of 26.62 seconds.
The old record of 26.67 seconds was set by Cameron van der Burgh of South Africa in July 2009, when swimmers were using performance-enhancing body suits.
"I feel absolutely amazing. I looked at the scoreboard about five times before I knew I had broken it," he said.
BBC Sport commentator Steve Parry
"I am in awe of this young man. Not everything was right technically but there will be more to come from him. He's such a strong lad and has enormous power but he can go quicker. He glided into the finish and still broke the record - imagine if he nailed the finish."
"I haven't broken a world record before so I don't know how it feels. Hopefully it will sink in by Saturday so I can get my head down and hopefully get a better performance out of myself in the final.
"I didn't expect this result even if I was close to the world record at the Commonwealth Games. It was not a perfect race due to my final touch so I can still improve tomorrow."
The City of Derby swimmer is competing at only his second major international event, having made his debut at last month's Commonwealth Games in Glasgow, where he won two golds and a silver for England.
The last Briton to break a world record was Liam Tancock, who set a best of 24.04 in the 50m backstroke at the 2009 World Championships in Rome, a time that still stands.
Peaty's record-breaking effort stole the limelight from another fine swim as Molly Renshaw won silver in the 200m breaststroke.
The 18-year-old touched behind the world record holder Rikke Moeller-Pederson of Denmark in a time of 2:23:82 to break the Kirsty Balfour's eight-year-old British record.
"I never expected to go that fast at the end of a long season," said Renshaw, who also won bronze and silver in the Commonwealth Games.
"I kind of hit a plateau in 2012 but I moved to Loughborough and things have been moving on and I've had an amazing summer."
Elsewhere, Stephen Milne finished fourth in the 800m freestyle final, and Jemma Lowe came sixth in the women's 100m butterfly.
In the men's 100m butterfly, Adam Barrett was second fastest as he made Saturday's final
Georgia Davies and Fran Halsall also qualified third and fourth fastest respectively for the final of the 50m backstroke.