Serena Williams rallied to defeat sister Venus Williams 3-6, 6-3, 6-4 on Thursday in a second-round matchup of Grand Slam champions at the WTA Top Seed Open.
Top-seeded Serena, a 23-time Grand Slam winner, said the victory will boost her confidence heading into the US Open as she improved to 19-12 in the 22-year-old rivalry with Venus.
"I wanted to win this for my game and my confidence," said Serena, whose only title as a mother came in January at Auckland.
"I honestly didn't come here to win (a title) for the first time in my career. I just came here to get some matches. I haven't had this much time off since I had the baby."
Ninth-ranked Serena is one shy of matching Margaret Court's all-time record of 24 Grand Slam titles and she is preparing to chase a seventh career US Open singles crown at Flushing Meadows.
Serena smacked a cross-court forehand winner to break Venus for a 2-1 lead in the third set, then dropped the next four games, only to break again in the seventh on another forehand cross-court winner, then hold to 4-4.
Serena zipped a backhand cross-court winner past Venus to break for a 5-4 lead and served out the match, aided by an umpire over-rule ace to reach 30-30.
Serena followed the call with her 14th ace and won after two hours and 19 minutes when Venus sent a forehand beyond the baseline.
"The last couple games I just wanted to win because I've been losing a lot of those tight sets," Serena said. "I just tried to focus on those last two games."
Serena improved to 100-110 after losing the first set, the best of any active WTA players. In the Williams sisters rivalry, the first-set winner has taken 26 of 31 meetings.
"This was right up there," Serena said. "I'd say it was one of the all-time top five super-competitive matches between the two of us."
Serena had six double faults and hit 67% of her first serves while winning 46% of second-serve points and taking 5-of-15 break points in her first event since February's Fed Cup.
Venus, ranked 67th, had six aces with 11 double faults. The seven-time Grand Slam champion ousted Victoria Azarenka in the first round.
Combined age of 79
"She played unbelievable," Serena said of Venus. "She's doing so good. I honestly don't know how I was able to pull it off at the end. She played so well."
Venus, 40, and Serena, 38, had a combined age of 79 years and 19 days, the third-oldest combined age of any WTA Tour match.
The sisters concluded matters with a racquet tap at the net, a nod to the COVID-19 pandemic that had shut down the season for five months until last week and forced the Lexington, Kentucky, event to be played without public spectators.
Serena advanced to a quarter-final on Friday against fellow American Shelby Rogers, who ousted Canadian teen Leylah Fernandez 6-2, 7-5.
Thursday's match marked the earliest Serena and Venus have met in a draw since their first tour-level meeting in the second round of the 1998 Australian Open.
Serena has won 10 of their past 12 meetings dating to Miami 2009.
It was the first match between the superstar siblings since the third round of the 2018 US Open, when Serena, in her comeback season from maternity leave, won 6-1, 6-2.
Also into the last eight was Jil Teichmann, who eliminated Kazak fifth seed Yulia Putintseva 6-2, 6-2. The Swiss next plays Catherine Bellis, who beat US compatriot Jessica Pegula 6-3, 6-2.
Results on Thursday from a WTA Tour event at Lexington, Kentucky (x denotes seed):
Serena Williams (USA x1) bt Venus Williams (USA) 3-6, 6-3, 6-4
Shelby Rogers (USA) bt Leylah Fernandez (CAN) 6-2, 7-5
Catherine Bellis (USA) bt Jessica Pegula (USA) 6-3, 6-2
Jil Teichmann (SUI) bt Yulia Putintseva (KAZ x5) 6-2, 6-2