OMAHA, Neb. -- Michael Phelps just missed setting another world record at the U.S. Olympic trials.

Natalie Coughlin and Aaron Peirsol showed him how to do it.

Racing about 10 minutes apart, Coughlin and Peirsol broke their own marks in the 100-meter backstroke Tuesday on another lightning-quick night.

Their records were the fifth and sixth of the meet -- with five days to go. Both Coughlin and Peirsol were wearing the Speedo LZR Racer, which upped its tally of world marks to 44 since debuting in mid-February.

"I'm really glad that I stamped my ticket to Beijing. I got that over with," Coughlin said. "I feel like a huge weight has been lifted."

Phelps made a dogged run at perhaps the most impressive record on his staggering resume, the time of 1 minute, 43.86 seconds from the 200-meter freestyle at last year's world championships. He was right on pace as he powered toward the wall, but he touched with only the third-fastest time in history, 1:44.10.

"The only thing I was not happy with was the last turn," Phelps said. "That's something little I can fix between now and Olympics."

Coughlin became the first woman to break 59 seconds in the backstroke, just one day after she reclaimed the world record in the preliminaries. She touched in 58.97, locking up the first of perhaps as many as six races she could swim in Beijing.

On Monday, Coughlin watched her world record in the 100 back snatched away by Hayley McGregory in the prelims. Two minutes later, Coughlin took it right back.

McGregory failed to even qualify for the Olympics. She finished third in Tuesday's final.

Peirsol showed he's still king of the backstroke, beating a strong field and his own record in the 100 back at 52.89, ahead of the 52.98 from last year's worlds.

Matt Grevers took second just ahead of Ryan Lochte, who withdrew from the 200 free final -- and another chance to race Phelps -- to give himself a better chance to qualify in the backstroke. The move didn't pay off; Lochte came on strong over the final 50 but touched in 53.37, behind Grevers' 53.19.

"That was probably the best field I've ever been in," said Peirsol, one of the Nike-sponsored swimmers who ditched their regular suit to wear the LZR Racer. "I don't think the Olympic field will be any harder than that."

In Tuesday night's other final, Jessica Hardy earned her first trip to the Olympics by winning the 100 breaststroke in 1:06.87.

Phelps returned to the pool about 50 minutes after the 200 free, posting the fastest time in the semifinals of the 200 butterfly at 1:54.02.

Virginia's Pat Reams was 13th overall in the semifinals of the men's 200 butterfly (2:00.16); only the top eight advanced to the final.

Reams had advanced to the semifinals by finishing 10th overall in the prelims (1:59.15) earlier in the day.

UVa's Lee Robertson and Ian Vogt were 38th (2:01.97) and 40th (2:02.04), respectively, in those prelims (2:02.04).

Recent William Byrd graduate Todd McGraw was 42nd (2:02.19) in those prelims. UVa's Daniel McMahon was 55th (2:03.13).

UVa's Claire Crippen was 43rd (2:18.84) in the prelims of the 200 individual medley. Teammates Liz Shaw and Megan Evo were 48th (2:19.00) and 49th (2:19.05), respectively.

In the 200 freestyle prelims, UVa's Jenna Harris was 78th (2:03.74).