No.3 seed Danielle Collins posted a comeback at the ATX Open on Thursday, but No.2 seed Sloane Stephens was upset by rival Anastasija Sevastova, who is continuing her solid return to tour after maternity leave.

Collins battled past fellow American Katie Volynets 4-6, 7-6(3), 6-0 on a chilly Thursday to return to the quarterfinals in Austin, Texas.

Collins, the former World No.7 and 2022 Australian Open runner-up, needed 2 hours and 19 minutes to turn around the matchup between last year's ATX Open semifinalists, which was the first meeting between the compatriots.

"It was challenging," Collins said after a match where she had multiple visits from the trainer. "I’ve had arthritis for a bunch of years now, and that’s something that I have to work through. There’s days that go well and everything feels great, and then there’s days like today where I have to work around stuff, and that’s half the challenge.

"I knew today when I woke up it wasn’t going to be great, and I just had to try to do everything that I could. It wasn’t ideal, but the main thing is that I figured out a way to win."

World No.112 Volynets served for the match at 6-4, 5-4, but 48th-ranked Collins gritted her way to a break and kept the match alive. Collins moved into high gear in the second-set tiebreak, where she won the last four points consecutively.

After claiming the second set by a narrow margin, Collins dominated the third set. She powered her way to three straight breaks of the Volynets serve, then saved two break points in the final game of the match before wrapping up victory with a forehand winner.

Collins had 39 winners to 24 unforced errors in the showdown and was a perfect 6-for-6 on break points. Collins is now into her second successive quarterfinal on tour; in her previous tournament, Collins made the Doha quarterfinals as a qualifier.

In Friday's quarterfinals, Collins will take on No.6 seed Wang Xiyu of China. World No.64 Wang dispatched Latvia's Darja Semenistaja 6-1, 6-2 on Thursday.

Highlights: Wang def. Semenistaja

The left-handed Wang is seeking her second hard-court title in the past six months. The 22-year-old won her first WTA singles title at Guangzhou in September of 2023.

Sevastova ousts Stephens: Later on Thursday, Sevastova of Latvia garnered a 6-3, 6-2 victory over American Stephens in just 1 hour and 12 minutes of play.

Former World No.11 Sevastova, currently ranked No.485, converted half of her 10 break points on the day, and she won eight of Stephens's 11 second-service points.

Highlights: Sevastova's finest forehands in victory over Stephens

Coming back from maternity leave, Sevastova played two WTA 125 events at the end of last year, reaching the quarterfinals both times. This year, she has played two WTA 250 events, and again she has made the quarterfinals on each occasion.

Sevastova continues her rivalry with Stephens, which she now leads 3-2. Two of their matches were high-stake matchups in US Open quarterfinals: Stephens won their 2017 battle in a third-set tiebreak en route to her Grand Slam title, but Sevastova knocked the defending champion out in the exact same round the very next year.

"With Sloane, we always have amazing matches," Sevastova said afterward. "Some of the most amazing matches in my career and the most important matches in my career I’ve played against Sloane.

"Today it was a bit different for both of us because it was so cold, and some delays -- like, I don’t know, it’s not even rain, it’s a mist delay; never happened to me before. But I managed to move my feet, just stay warm, and put pressure on her."

In their first match since that 2018 showdown, Sevastova and Stephens were deadlocked at 3-3 before going off court for a 45-minute rain delay, which was the second weather interruption of the night. 

Upon their return, Sevastova took charge, winning the last 11 points of the first set. The Latvian then cruised through the second set, with one final unreturned forehand sealing victory.

Highlights: Schmiedlova def. Vickery

Sevastova will play Anna Karolina Schmiedlova of Slovakia in the quarterfinals. Sevastova holds a 4-0 head-to-head lead over Schmiedlova.

Late on Thursday night, Schmiedlova won a long affair against Sachia Vickery, prevailing 5-7, 7-6(5), 7-5 in 2 hours and 50 minutes. Schmiedlova avenged a loss to Vickery at last week's WTA 125 event in Puerto Vallarta.