Michael Phelps beat rival Ryan Lochte to win the 200m freestyle final at the US Olympic trials in Omaha as both secured their places at London 2012.
Reigning Olympic champion Phelps clocked a time of one minute 47.70 seconds, just 0.05s ahead of Lochte.
American Missy Franklin, 17, booked her maiden Olympic berth after winning the 100m backstroke.
However, defending Olympic champion and two-time gold medalist Natalie Coughlin failed to qualify.
Phelps and Lochte had already sealed spots in the 400m individual medley, with Lochte finishing ahead of his rival on Monday.
However, Phelps, who won a historic eight Olympic gold medals in Beijing four years ago to take his overall tally to 14, turned the tables on Lochte in the 200m freestyle final, leading throughout to take victory.
Phelps's winning time was almost four seconds outside Paul Biedermann's world record, and he accepts that better will be needed in London.
"In my eyes, 1:45.70 is not going to make the medal podium," he said.
Lochte, meanwhile, is relishing renewing his rivalry with Phelps at the Olympics.
He said: "I love that race. I love racing against him. I could be a pool length ahead of him and he'll still be there at the end. He's a great racer."
There are high expectations of Franklin at the Olympics following her breakthrough performance at last year's World Championships, and she was impressive in the 100m backstroke final at the trials.
She surged into the lead on the second lap to win in 58.85s, an American record and the fastest time in the world this year.
"I have dreamed of this moment but I never thought it would come true at 17 years old," she said. "Dreams do come true."
Rachel Bootsma, 18, was second in 59.49s to secure her place in London, while Coughlin, 29, finished third and missed out on the chance of a third gold medal.