Michael Phelps celebrated his 27th birthday by beating his great rival Ryan Lochte in their penultimate showdown before the London Olympics on Saturday.
For the third time this week, the pair battled each other stroke-for-stroke at the US Olympic trials in America's Midwest, this time in the 200 metres individual medley.
Lochte beat Phelps in the 400m individual medley on Monday but Phelps avenged that loss when he got his hand on the wall first, stopping the clock at one minute 54.84 seconds.
Lochte, who had won the 200m backstroke final just 30 minutes before taking on the greatest Olympian of all time, was just 0.11 seconds behind, setting the stage for another epic duel in London when both men should be at their peak.
Phelps has already qualified for four events in London and looks certain to add a fifth after setting the fastest time in the semi-finals of the 100m butterfly.
With the addition of the three relays, he will swim the same eight events he contested at Athens and Beijing.
Lochte also qualified for the 100m butterfly final after swimming three races in less than hour on Saturday.
The 27-year-old has already clinched his place in four events but unlike Phelps, is not assured of a place in all three relays.
Teenage sensation Missy Franklin looks set to compete in seven events at her first Olympics after the 17-year-old finished runner-up in the 100m freestyle final and set the fastest qualifying time for Sunday's 200m backstroke final.
Like Lochte, she was back in the pool within half an hour of her previous race and finished second in 54.15, behind Jessica Hardy (53.96), who booked her first trip to the Olympics after being forced to miss Beijing over a doping offence.
Hardy was suspended after testing positive for the banned steroid clenbuterol at the 2008 US Olympic trials.
The offence normally carries a two-year ban but she was given a reduced penalty after explaining she took nutritional supplements having obtained assurances from the manufacturer, only to discover later that they were contaminated.
Despite her explanation, she fought a long and bitter legal case against anti-doping officials, who wanted her banned from London as well.
Natalie Coughlin sneaked in to the team for her third Olympics when she finished sixth in the 100m freestyle final, securing a place in the relay after missing out in her individual events.
But Amanda Beard, who won her first gold as a 14-year-old in Atlanta in 1996, failed to qualify for a fifth Olympics when she could only manage fifth in the 200m breaststroke final behind world and Olympic champion Rebecca Soni.
Katie Hoff, who won five events at the 2008 US trials but was unable to win a gold in Beijing, failed in her last chance to make a third Olympics when she finished 13th in the women's 800m freestyle after struggling all week with a virus.
"Obviously I wanted to do better but I gave it my best shot," Hoff said.
"I'm actually proud of myself for doing it. Somebody told me my career is about not rolling over in adversity. I don't want to be that girl."
The 800 heats also marked the end of a brief comeback for former Olympic champion and world record holder Janet Evans.
The 40-year-old mother of two retired after the 1996 Atlanta Games but decided to have one last shot at making another Olympics but finished a lowly 53rd in the preliminaries.
"This became more for me than just trying to make the Olympics," Evans said.
"I could have slept in every day and played with my kids but this was just about trying something different and I'm so proud of myself for getting this far.
"But this is definitely it. I just signed my retirement papers."