Aaron Peirsol on Friday. (Reuters)

Rome: Aaron Peirsol ripped up his own world record to win the men’s 200 metres backstroke final at the World Championships on Friday.

The American swam one minute 51.92 to beat the mark of 1:53.08 he set earlier this month. Japan’s Ryosuke Irie was second with Ryan Lochte of the United States third.

In the women’s 100 metres freestyle, Germany’s Britta Steffen set the world record of the world championships in 52.07 seconds. Steffen was trailing Australia’s Libby Trickett at the turn of Friday's race, but she was too strong for everyone on the return lap. The German broke the mark of 52.22 that she set swimming the leadoff leg of the 400 free relay last Sunday.

Marleen Veldhuis of the Netherlands won the first semi in 25.28 seconds, eclipsing her own mark of 25.33 set in April. She got to keep the record less than five minutes — Sweden’s Therese Alshammar won the next semi in 25.07.

Sweden’s Therese Alshammar broke the women’s 50 metres butterfly world record. Defending champion Alshammar swam 25.07 to win her semi-final and beat Dutch swimmer Marleen Veldhuis’s mark of 25.28.

Meanwhile, Milorad Cavic sent quite a message heading into his showdown with Michael Phelps in the 100 metre butterfly, setting a world record and nearly becoming the first swimmer to break 50 seconds.

The Serbian got off to his usual strong start — he was a second under the world-record pace at the turn — and held on at the end for a time of 50.01 in Friday’s semifinals.

That broke the mark of 50.22 set by Phelps at the US nationals on July 9. Phelps won the other semifinal in 50.48. (Agencies)