Serena Williams came back from the brink to win the much-anticipated 31st meeting with her sister Venus and reach the quarterfinals of the inaugural WTA tournament in Lexington.
Two days after coming within a few points of defeat against Bernarda Pera, Serena found herself in a similarly precarious position against Venus in the last 16.
In the 31st professional meeting between the superstar sisters, Serena trailed 4-2 in the final set before completing a 3-6 6-3 6-4 victory in two hours, 19 minutes.
She will next face Shelby Rogers, a straight-sets winner over Canadian rising star Leylah Fernandez, for a spot in the semis.
Serena joins Coco Gauff in the Lexington quarterfinals; on Wednesday, the American teen star upset No.2 seed Aryna Sabalenka in three torrid sets.
It was a similarly tough battle for Simona Halep at the concurrent WTA clay-court tournament in Prague.
Like Serena, Halep was stretched to three sets for the second time in a row before eventually beating Barbora Krejcikova 3-6 7-5 6-2.
The Romanian followed a resurgent Eugenie Bouchard into the quarterfinals; the Canadian earlier on Thursday overcame Tamara Zidansek 7-6(2) 6-7(2) 6-2.
Venus-Serena XXXI
But back to the match which most ignited the interest of tennis fans worldwide, and one that Serena looked to have taken control of when she pocketed the second set and went ahead a break in the third.
Venus rallied, reeling off three consecutive games to take a commanding lead, but Serena wasn’t done.
The 23-time Grand Slam champion produced a forehand winner to break back in the seventh game, and a searing backhand winner up the line to break again for a 5-4 lead.
Serving for the match, she didn’t falter, finishing the contest with 14 aces.
“I feel like today I turned it up in the last two games. I really needed to just play better,” Serena said.
“I think it was a very high-quality match. Venus is playing really, really good. It was a lot of long points and running me around. We both started serving really well and then we were both returning well. I think it was really good.
“I don’t care (who I play). I’m just kind of here just to play another match, and just to get match tough for New York.”
The US Open begins on 31 August, a tournament where last year she reached the final.
There she fell to Bianca Andreescu, who announced on Thursday that she would not defend her title.
“I have taken this step in order to focus on my match fitness and ensure that I return ready to play at my highest level,” the 20-year-old Canadian wrote on social media.
“I will miss not being there. However, I realize that the unforeseen challenges, including the Covid pandemic, have compromised my ability to prepare and compete to the degree necessary to play at my highest level.”
The men's draw will include the world No.1, however, after Novak Djokovic confirmed he is heading to New York.
"It was not an easy decision to make with all the obstacles and challenges on many sides, but the prospect of competing again makes me really excited," said the Serb.
Halep, Bouchard advance in Prague
World No.2 Halep endured another tough outing on the clay in Prague, two days after requiring seven match points to see off Polona Hercog.
The top seed led wildcard Krejcikova 5-2 in the second set yet missed four set points two games later which allowed the Czech to level scores at 5-5.
Halep corrected course and sent the match to a third set, where she fell behind 0-2 before racing though six straight games to secure victory.
“I didn’t feel great. My energy was not great,” Halep admitted. “But sometimes it’s more important to win the matches that you are not playing great. You just fight, and you just find a way.”
Halep will play Polish lucky loser Magdalena Frech for a place in the semifinals.
Former world No.5 Bouchard, currently ranked 330th and who required almost three hours to subdue Zidansek, set up a quarterfinal meeting with third seed Elise Mertens.