Fina World Championships
Date: 17 July-2 August (swimming from 26 July) Venue: Rome
Live/highlights on BBC Two, Red Button and BBC Sport website
Replay - Biedermann shatters Phelps record (UK users only)
Germany's Paul Biedermann beat Michael Phelps in the men's 200m freestyle final to win gold - obliterating the American's world record in the process.
Biedermann led from the second turn and finished in one minute 42.00 seconds, beating Phelps' record by 0.96.
The 22-year-old adds the 200m title and record to the 400m title and world best he achieved on Monday.
Phelps, who touched home in 1:43.22, suffered his first major individual loss in four years.
That occurred at the 2005 World Championships when Ian Crocker beat him in the final of the 100m butterfly.
The 24-year-old, who won eight gold medals at the 2008 Beijing Olympics, said fatigue cost him in the last part of the race.
"I'm a little disappointed that I kind of got tired in the last 20m, 30m of that race," said the American, who picked himself up after the defeat to qualify second fastest for Wednesday's 200m butterfly.
"Biedermann just took off, he took it to a new level in that race, that's a good swim for him.
"He's come down a lot in the last year and I think it's going to be fun next year when swimming's back to swimming."
The German champion was overjoyed with his sensational win.
I hope there will be a time I can beat Michael Phelps without the suit of course
"For the moment it is just like a dream," he said. "It's such an amazing feeling. I'm so fine."
Biedermann wore a 100% polyurethane swimsuit which has been worn by all but one of the individual swimming champions in Rome. Phelps wore a part-polyurethane costume.
The German strongly hinted that he may not have won gold had it not been for his suit.
"I hope there will be a time I can beat Michael Phelps without the suit of course and I hope that it could be next year or the next two years but I also think it's not all about the suit," he added.
"Of course they make a difference but I work really hard with my trainer so it's one of the things which is important to the swimming and also to the training."
In total, four world records fell on Tuesday to take the total at these championships to 15.
Britain's Gemma Spofforth broke the 100m backstroke record to win gold, while Italy's Federica Pellegrini sent the home crowd wild with her superb performance in the 200m freestyle semi-final.
The Italian, who smashed her own world record to win Sunday's 400m final, cruised to 1:53.67 to better her 1:54.47 mark she set in March.
The host nation also struck gold when Alessia Filippi captured the women's 1500m freestyle title in 15:44.93, ahead of Denmark's Lotte Friis and Romanian Camelia Potec.
The other world record of the night went to Cameron van der Burgh who set a new best in his 50m breaststroke semi-final.
The South African posted 26.74 seconds to eclipse Felipe Franca da Silva's previous time of 26.89.
In Tuesday's other finals, American Rebecca Soni, who set a world record in the 100m breaststroke semis, recorded a slightly slower 1:04.93 to win gold.
And Japan's Junya Koga came though fast at the end to take the men's 100m backstroke title in 52.26, ahead of Germany's Helge Meeuw and former world record-holder Aschwin Wildeboer of Spain.