OMAHA, Nebraska - Natalie Coughlin and Aaron Peirsol blitzed to back-to-back world records in the 100 metres backstroke to highlight another breathless day of action at the US Olympic swimming trials on Tuesday.

Natalie Coughlin celebrates her new mark in the 100m backstroke at the US Olympic swimming trials on Tuesday. [Xinhua]

Coughlin sparked the record demolition when she stormed to the wall in a time of 58.97 seconds, trimming 0.06 seconds off her own mark to become the first woman to dip under 59 seconds.

It marked the third time in two days the record had been lowered, with Hayley McGregory and Coughlin swapping the mark in successive preliminary heats on Monday.

Aaron Peirsol celebrates to win the men's 100 metre backstroke setting a new world record time of 52.89 seconds at the U.S. Olympic Swimming Trials in Omaha, Nebraska July 1, 2008. [Agencies]

With the crowd still buzzing over Coughlin's performance, Peirsol brought them to their feet again powering home in a time of 52.89 seconds to beat his own record of 52.98 set at last year's world championships in Melbourne.

Six world records have now tumbled in the first three days of the trials.

Michael Phelps narrowly missed sharing in the world record blitz, clinching his second Olympic berth cruising to victory in the 200m freestyle in 1:44.10, the third fastest time ever.

Less than 40 minutes later, the six-time Olympic gold medal winner was back in the spotlight clocking the top qualifying time of 1:54.02 in the 200m butterfly.

In the night's only other final, Jessica Hardy booked a ticket to her first Olympics winning the 100m breaststroke in 1:06.87 ahead of 2000 Sydney gold medallist Megan Jendrick.

Katie Hoff, who has already claimed one world record (400 IM) and two Olympic spots (400 IM, 400 free) looks poised to add to more events to her Beijing programme posting the top times in both the 200m free and 200m individual medley.