OMAHA, NEBRASKA (AFP) - Nathan Adrian stormed home to win the 100 metre freestyle at the US Olympic swimming trials, punching his ticket to Rio where he'll go for a second straight gold.

Adrian clocked 47.72sec, improving on the 47.91 he produced in the semi-finals. Only Cameron McEvoy of Australia (47.04) has gone faster in 2016.

The 27-year-old Adrian was just one veteran in the spotlight on Thursday as superstar Michael Phelps and Ryan Lochte lined up a tantalizing 200m individual medley clash with semi-final victories.

Phelps comfortably won the first semi in 1:57.61. Lochte followed with a 1:56.71 that makes him the second-fastest in the world this year.

"It's going to be good," Phelps predicted of Friday's final. "You'll have an exciting race."

Phelps will be gunning to add the 200m medley to a Rio slate that already includes the 200m butterfly.

Lochte, meanwhile, will be in search of a first individual Rio berth as he and Phelps add another chapter to a rivalry more than a decade old.

Adrian, who beat Australian James Magnussen to the 100m free gold in London by one one-hundredth of a second, had not cracked 48 seconds since 2013.

Now that he's done it twice in as many days, he's looking forward to taking on another Aussie challenger in McEvoy.

"I just look forward to racing him," Adrian said. "There is nothing more fun than getting the best guys in the world together in the same pool and just seeing what happens."