Al Bello, Getty Images
Hayley McGregory and Natalie Coughlin take off for the final of the 100-meter backstroke. Coughlin went on to set a world record.

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 at the temporary pool in America's heartland.

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.

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.

Coughlin became the first woman to break 59 seconds, 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.

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.

Six-foot-8 Matt Grevers took second just ahead of Ryan Lochte, who dropped a spot in the 200 free final — and another chance to race Phelps — to give himself a better shot to qualify in the backstroke. 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. He'll head to Wednesday's final as a big favorite. As for the 200 free, one minor mistake probably cost him a new record.