HOUSTON (AFP) — World record-holder Gretchen Walsh clocked 55.60 seconds to win the 100-meters butterfly on Friday at the US Open in Austin, Texas, where swim stars Summer McIntosh and Leon Marchand again tested themselves in unfamiliar events.

Walsh’s US teammate Regan Smith was second in the 100m butterfly in 56.18 and Canadian McIntosh produced a personal best of 57.01 to finish third in an event she rarely swims.

McIntosh, winner of three gold medals at the Paris Olympics and four titles at the World Championships in Singapore this year, chose to challenge herself in 100m races, foregoing her trademark 400m individual medley.

So did France’s Marchand, a four-gold winner in Paris who, like McIntosh, trains in Austin with former Michael Phelps mentor Bob Bowman.

McIntosh, competing for the first time since she joined Bowman’s group, also finished seventh in the 100m backstroke and eighth in the consolation final of the 100m breaststroke.

Smith came back from her runner-up finish in the 100m fly to win the 100m backstroke in 58.19 seconds. The world record-holder in the event, Smith was 52 hundredths in front of second-placed Katharine Berkoff.

Marchand posted a personal best of 51.20 seconds to finish third in the 100m butterfly won by American Shaine Casas in an impressive 50.24 seconds.

Canadian Ilya Kharun was second in 50.40 seconds and world record-holder Caleb Dressel, trying to work his way back to the international stage after a lengthy break from the sport, was fourth in 51.33 seconds.

American Kate Douglass, the reigning world and Olympic 200m breaststroke champion, won the 100m breaststroke in one minute and 06.55 seconds.