US teen Coco Gauff notched another impressive victory on Wednesday, toppling second-seeded Aryna Sabalenka 7-6 (7/4), 4-6, 6-4 to reach the quarter-finals of the WTA tournament in Lexington, Kentucky.
Gauff, playing her first tournament in the coronavirus-disrupted season since she stunned defending champion Naomi Osaka at the Australian Open, lined up a quarter-final clash with eighth-seeded Tunisian Ons Jabeur, a 3-6, 6-2, 6-4 winner over Olga Govortsova.
"I'm just happy to have pulled it through today," Gauff said after coming out on top in a see-saw battle that lasted two hours and 24 minutes.
Up 5-2 in the first set, the 16-year-old American would need a tie-breaker to put it away.
Sabalenka, who won her third career Premier 5 title in Qatar before the WTA Tour was suspended because of the Covid-19 pandemic, took a 5-2 lead in the second set and held off a challenge from Gauff to knot the match at a set apiece.
The third set opened with a string of service breaks, Sabalenka twice clawing back a break.
But Gauff gained a break to lead 5-4 and served out the match with an angled forehand winner.
"It was all about staying calm and composed, making her play balls," Gauff said. "In the second set, I hit more double faults and errors, so my goal for the third was to change that."
Gauff, who won her first WTA title at Linz last year, said she had room to improve on her serve.
"I definitely served better in my first match than today, but you're going to have good and bad days," she said, "and I like to go for my serves, so that's the give and take."
In other second-round matches on Wednesday, Czech Marie Bouzkova beat Russian Anna Blinkova 6-4, 6-2. She will now play American Jen Brady, who beat sixth-seeded Magda Linette of Poland 6-2, 6-3.
The marquee match of the second round was set for Thursday, with top-seeded Serena Williams due to take on sister Venus.
Serena shrugged off the absence of fans in a come-from-behind victory over Bernarda Pera on Tuesday, the 23-time Grand Slam champion's first competitive match since a Fed Cup appearance in February.
Venus Williams beat former world No 1 Victoria Azarenka to set up the mouth-watering match-up with her younger sister - their first since the 2018 US Open.
"It has been quite the draw for me, but quite honestly, this is perfect, because I haven't played in forever, so I want to play the best players," Venus said. "And I think I got my wish playing Serena, so here we go."
Scores from Wednesday's matches at the WTA Top Seed Open in Lexington, Kentucky (x denotes seed):
Ons Jabeur (TUN x8) bt Olga Govorotsova (BLR) 3-6, 6-2, 6-4
Marie Bouzkova (CZE) bt Anna Blinkova (RUS) 6-4, 6-2
Coco Gauff (USA) bt Aryna Sabalenka (BLR x2) 7-6 (7/4), 4-6, 6-4
Jen Brady (USA) bt Magda Linette (POL x6) 6-2, 6-3