The first Phelps Vs Lochte showdown, with Tyler Clary in the wings for potential upset, is on the boil after the 400m medley heats at US Olympic trials in Omaha had the world champion from the Florida Gators on 4:10.66 and the world record holder - Spitzean moustache shaved off for the occasion - on 4:14.72, his Baltimore teammate Chase Kalisz on 4:15.78 and Clary on 4:15.88.

"I know I have to be a lot faster tonight," Lochte told reporters. With a nod to the world record holder,. he added: "I think that is the easiest 4:14 he's ever done … the easiest that I've ever seen in the entire world."

Phelps said he felt "all right", while Clary was surprised to see the Olympic champion there four years after Phelps said he would drop the event after his Beijing victory.

"That did come as a surprise, but it doesn't change my game plan," Clary told reporters. "It will definitely be a more interesting race."

Another world champion in great warning-shot form this morning in Omaha was Dana Vollmer, on the world's best time of 2012, 56.59, just 0.12sec shy of her US record. Natalie Coughlin was fourth fastest through in 58.41, with Claire Donahue, 57.82, and Elaine Breeden, 58.38, splitting the Cal teammates.

In the men's 400m free, Connor Jaeger, clocked 3:48.06 to progress at the helm of a tight field closed in 3:49.89, international experience in the mix with Peter Vanderkaay and Michael Klueh among those through.

World champion Gator Elizabeth Beisel led the way in the 400m medley, on 4:35.72, with two others inside 4:40, Caitlin Leverenz on 4:39.57, and Cammile Adams on 4:39.84.

John Criste clocked 1:00.29 to lead the way through in the 100m breaststroke. Among his training partners at Trojan is Kosuke Kitajima, nemesis of the next man home this morning, former world record holder Brendan Hansen, of Texas Longhorns, on 1:00.30. Mark Gangloff clocked 1:00.43 as the third of six men through inside 1:01.