Michael Phelps, Ryan Lochte hog spotlight from Olympic qualifiers

The evening got off to an electrifying start with Prenot chasing down Kevin Cordes to win the men's 200 breaststroke in a sizzling time of two minutes, 7.17 seconds, the second fastest ever in the event and just 0.10 seconds off the mark held by Japan's Akhiro Yamaguchi.

But it is how the night finished with Olympic champion Phelps and world champion and world record holder Lochte cruising to easy wins in their 200 medley semifinals that had the swim world buzzing setting up one more showdown between the longtime rivals in Friday's final.

While Phelps has already secured a spot on his fifth US Olympic squad and Lochte his fourth, Prenot's race represented his last chance to Rio.

Cordes, winner of the 100 breast, went out at a blistering pace making the last turn 1.19 seconds under world record pace.

But the 22-year-old could not hold on over the final 50 metres as Prenot beat him to the wall to qualify for his first Olympic team.

"This is my last race, my last chance to make the team," said Prenot. "I didn't feel like waiting another four years, so the pressure was on."

Adrian is also headed to Rio with a chance to defend the 100 metres freestyle gold he won at the London Olympics after blazing to victory in a time of 47.72 in swimming's blue riband event.

He was followed to the wall by Caeleb Dressel, Ryan Held and Anthony Ervin, the top four all qualifying for the relay team.

Adams, who was disqualified in the 200m butterfly heats and then reinstated, took advantage of her second chance clinching her Olympic berth with a timing of 2:06.80.

"It's been crazy," said Adams. "I've learned about myself how to overcome obstacle and obviously yesterday was an obstacle that I never thought I would be able to overcome."

Abbey Weitzeil, bidding to make her first Olympic team, upstaged some of biggest names in U.S. swimming posting the fastest time of 53.57 in the semi-finals of the women's 100 free.

Katie Ledecky, who is battling Phelps for top billing at the trials and has already secured Olympic spots in the 200 and 400 free, will try to add the 100 to her Rio dance reaching Friday's final with the seventh fastest effort of 54.04 ahead of Allison Schmitt, the 200 free gold medal winner at the 2012 London Games.