Danielle Collins, Sloane Stephens and Sofia Kenin move forward at San Diego Open

SAN DIEGO (AP) — Danielle Collins beat qualifier Louisa Chirico 7-5, 6-0 in singles at the Cymbiotika San Diego Open on Tuesday and then joined CoCo Vandeweghe of nearby Rancho Santa Fe for a 6-3, 4-6, 10-3 doubles victory against Marta Kostyuk and Alycia Parks.

"The last couple of days, I hadn't gotten a lot of court time. I got sick after the US Open. There was a bad bug going around," Collins, ranked No. 43 in the world, said after beating fellow American Chirico. "I kind of needed to be out here a little longer, so I was happy we were playing some long points, and had some long games. I was just trying to find my rhythm."

She found that rhythm against Chirico. Knotted at 5-all in the tight opening set, Collins, a finalist at the Australian Open last year, reeled off eight unanswered games to win the match in 70 minutes and advance to the second round.

Like Collins, Kostyuk was pulling double duty on Tuesday. The world No. 29 defeated Poland's Magda Linette in singles, 6-2, 7-6 (5).

On the heels of a disappointing first-round exit in Flushing Meadows, where she raised the U.S. Open trophy in 2017, Sloane Stephens came out fast against Belgian Elise Mertens, winning 6-1, 6-3.

"She's obviously a great player, but I'm playing here in San Diego, in Southern California, with all my friends and family. It's not very hard to get pumped up to come out and play," said Stephens, who earned a second-round matchup with No. 2 seed Caroline Garcia of France. "I'm just really pleased to be playing some good tennis and to come out with a win."

Sofia Kenin continues to claw her way back up the rankings after reaching a career-high No. 4 in 2020, the year she captured her first Grand Slam title at the Australian Open. Now ranked No. 93, she upended No. 6 seed Veronika Kudermetova 6-4, 6-4.

Kenin, one of eight Americans in the main draw, had ample reason to bring her best game. In addition to the rankings incentive, Hall of Famer Rod Laver was seated courtside.

"On the changeover, I heard he was here. I was like, ‘OK, try to do well for him,'" Kenin said. "I had to fight. Of course, she was going to pick up her game, and I kind of let down a little bit and made some unforced errors, but I was luckily able to pick it up and close it out."

Fresh off a career-best quarterfinal appearance at the US Open, Latvia's Jelena Ostapenko outlasted eighth-seeded Ekaterina Alexandrova in a 2-hour and 46-minute battle, 7-6 (3), 6-7 (6), 7-5.