Michael Phelps's run of invincibility ended yesterday as Germany's Paul Biedermann seized the 200m freestyle world title and world record from the US Olympic champion.
Biedermann handed Phelps his first individual defeat in world and Olympic competition since 2005, triumphing in 1 minute 42 seconds.
"It's amazing to beat Michael Phelps," said Biedermann, who broke the world record of 1:42.96 Phelps set in winning gold at the Beijing Games.
"I was there in Beijing when he won his eight gold medals and it was a great moment for me to live this moment," Biedermann said. "Now that I'm faster than him, it was a dream for me and I feel absolutely great about this."
Phelps settled for silver in 1:43.22, with Russia's Danila Izotov third in 1:43.90.
The American hadn't been beaten in individual world or Olympic competition since losing to Ian Crocker in the 100m fly final at the 2005 worlds in Montreal.
Phelps, who took six months off after the Beijing Games, the longest break of his competitive career, tried to be philosophical, but it was clear the defeat stung.
"Theoretically that was a pretty good swim for me," the 24-year-old said.
"Three-tenths off my best time after taking six months off.
"I'm not happy, but I know I didn't train much this year. For right now I'll take it - but I'm not pleased."
Phelps didn't have time to dwell on the defeat as he returned to the water for the semi-finals of the 200m butterfly and notched the second-fastest time leading into today's final behind Japan's Olympic bronze medallist Takeshi Matsuda.
Biedermann's was the first of four world records yesterday, taking the total from three days of swimming to 15.
Britain's Gemma Spofforth won the women's 100m backstroke title in a world record 58.12. Russian Anastasia Zueva had set the previous record of 54.48 in the semi-finals on Monday, but her 58.18 was only good enough for silver. Australia's Emily Seebohm was third in 58.88.
Italian fans were treated to a home world record and a world title - from two different swimmers.
Alessia Filippi captured the women's 1,500m freestyle title in 15:44.93, ahead of Denmark's Lotte Friis and Romanian Camelia Potec.
Federica Pellegrini lowered her own world record in the 200m free with a time of 1:53.67 in the semi-finals, and South Africa's Cameron Van Der Burgh clocked a world record of 26.74sec in the men's 50m breaststroke semi-finals.
Junya Koga won the men's 100m backstroke in 52.26 seconds. Germany's Helge Meeuw, sixth at the turn, rallied to take silver in 52.54 and former world record-holder Aschwin Wildeboer of Spain was third in 52.64.
American Rebecca Soni, who set a world record in the 100m breaststroke semis on Monday couldn't repeat the feat, but she captured the world title in 1:04.93.
Andrea Agius sets record
It was the turn of Andrea Agius to make the headlines for Maltese swimming yesterday after breaking the national 50m breaststroke record in a time of 30.55 seconds when finishing fourth in his early morning heat.
Agius's time was 0.44 seconds inside his own previous record he set at the national championships last month. It was the fourth national record during the Rome championships. Other swimmers involved in yesterday's morning heats were Neil Agius, who covered the 800m freestyle in 8 minutes 54.06 seconds, 4.62 seconds outside his own national limit, Talisa Pace who clocked 2:14.08 in the 200m free and Melinda Sue Micallef, who unfortunately was disqualified in the same event.