Olympic champion Katie Ledecky (Bethesda, Md.) won the women’s 400-meter freestyle, and took second in the 100m free, while Michael Phelps (Baltimore, Md.) claimed the men’s 100m butterfly on the opening night of the Arena Pro Swim Series at Austin.

After taking second in the 100m free in a lifetime-best 53.75 seconds in the first event of the session, Ledecky clocked a time of 3:59.54, the fifth-fastest in history, to win the 400m free at the University of Texas’ Lee & Joe Jamail Texas Swimming Center.

“I think going under four minutes was really good coming off the hundred, and I can still take away a lot of things coming off those two races,” Ledecky said.

In the 400m free, she now owns four of the top five performances all-time, including the world record.

Fellow world record-holder Phelps closed quickly over the final 50 meters to win the men’s 100m fly in 51.94, ahead of Tom Shields (Huntington Beach, Calif.) in 52.39 and Tim Phillips (Vienna, W.Va.) in 52.61.

“I’m happy to be able to do that double and go 51.9,” said Phelps, who also swam 49.77 in the men’s 100m free, good for sixth.   

Sweden’s Sarah Sjostrom also had a big night winning the women’s 100m free and 100m fly in U.S. Open record fashion. She won the women’s 100m free in 53.12, followed by Ledecky. Sjostrom then came back later in the session to set a second U.S. Open mark in the women’s 100m fly, touching in 56.38 to best runner-up Dana Vollmer (Granbury, Texas), who was second in 57.61.

Reigning Olympic champion Nathan Adrian (Bremerton, Wash.) took the men’s 100m free victory in 48.91. Former Texas standout Laura Sogar (Exeter, R.I.) won the women’s 200m breast in 2:24.69, Josh Prenot (Santa Maria, Calif.) took the men’s 200m breast in 2:10.26 and France’s Jordan Pothian took the men’s 400m free in 3:50.06.

The meet continues through Sunday with daily prelims at 9 a.m. Central followed by finals at 6 p.m.

The Arena Pro Swim Series at Austin is the second of seven stops 2015-16 Arena Pro Swim Series. As part of USA Swimming’s partnership with swimwear leader Arena, the circuit will feature a record $350,000 in overall prize money. Swimmers may earn awards for top-three finishes in all individual Olympic events across the series. At each meet, $1,000 will be provided for a first-place finish, $600 for second and $200 for third. In addition to the single-event prize money, the overall male and female winners of the season-long Series will earn a $10,000 bonus.

For the third consecutive season, longtime USA Swimming partner BMW will award the grand prize of a one-year lease of a BMW vehicle to the highest-scoring eligible male and female U.S. swimmers.

Male and female overall Arena Pro Swim Series champions will be honored at the conclusion of the 2015-16 series based on the number of points accumulated throughout the seven meets. Participants will be awarded points in each individual Olympic event throughout the duration of the Series (Five points for first, three for second, one point for third place).