Michael Phelps moved closer to superceding Ian Thorpe as the world's best swimmer after a stunning night at the World Championships in Barcelona.
The 18-year-old American destroyed the world record in the 200m individual medley as he relegated Thorpe to second in their much-anticipated showdown.
And that performance came less than an hour after he had broken the 100m butterfly world record in the semi-finals, a mark that had been set moments earlier by Ukrainian Andrii Serdinov.
The Baltimore native is the first swimmer in history to break two world records in two different individual events on the same day.
"I'm excited for sure," Phelps said. "After the 100 fly world record I was very fired up. So I just went out there and laid it on the line in the first 100 and tried to hang on."
The 100m fly record gave Phelps a world mark in his fourth different discipline. No other current male or female swimmer holds four individual records.
On Tuesday, he broke his own world record in the 200m butterfly with a time of 1:53.93.
He also holds the 400m individual medley world record, the 400 IM semi-finals and finals are Sunday on the final day of the championships.
Phelps could match Mark Spitz's seven Olympic gold medals in Athens next year as he targets gold in four individual events and three relays.
Thorpe (left) and Phelps are vying to be the world's best swimmer
Phelps' triumph completed a highly successful evening for the American team.
Aaron Peirsol successfully defended his title over 200m backstroke, while Amanda Beard equalled the world record as she took gold in the 200m breaststroke.
But Beard's team-mate Jenny Thompson was out of luck in the 100m freestyle.
The veteran was beaten into bronze medal position by Finland's Hanna-Maria Seppala and Australia's Jodie Henry.
Australia's Grant Hackett cruised to victory in the 800m freestyle, but Britain's Graeme Smith just misses out on the medals in fourth.
Britons Sarah Price and Katie Sexton both booked their places in the final of the 200m backstroke by finishing second in their semi-finals.