American Michael Phelps and Australia's Jessicah Schipper broke the world records in the men's and women's 200 meters butterfly at the Pan Pacific championships in Victoria, Canada, on Thursday.
Phelps, 21, broke his own 200m butterfly mark in the next race of the evening, clocking one minute 53.80 seconds to shave off 0.13 seconds from his previous best.
Phelps, who won six gold medals at the Athens Olympics in 2004, was pushed by Japan's Ryuichi Shibata until the final 50 meters before the American surged clear.
"It's a good start to the meet. I've wanted to do a best time in that event for a while now. I saw the other guys do well this morning, so I knew it would be close at the 150.
"But (coach) Bob (Bowman) and I were talking about having a strong kick off the last wall. I did that and was able to build some good momentum.
"When the crowd is cheering like that you always know something good is happening."
Shibata finished second in 1:55.82. Phelps's previous record was set in Barcelona in 2003.
Schipper, the 100m butterfly world champion, clocked world record splits throughout the race before winning in two minutes 5.40 seconds.
Her time was 0.21 quicker than the previous record set at last year's world championship final in Montreal by Poland's Otylia Jedrzejczak.
Schipper finished second in that race behind the Pole, who controversially kept the title and record despite television footage showing that she touched the wall with just one hand.
"I heard the crowd, and it really helped me. It's just amazing to break the world record, I can't believe it," Schipper told the swimnews Web site.
Schipper finished well clear of the field, with Japan's Yuko Nakanishi claiming second in 2:06.52 and team mate Yurie Yano third.
