Wimbledon champion Elena Rybakina saved three match points before falling 6-2, 6-4 to Madison Keys on Friday in the ATP and WTA Cincinnait Masters quarter-finals.
The Kazakh, who lifted the All England Club trophy last month against the odds, exited the pre-US Open event in 92 minutes as she went down to the American titleholder from 2019.
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The pair struggled through a 21-point, 12-minute opening game, with Keys then turning on her jets to win the second in seconds.
Keys also came from a break down in the second set to carve out victory.
Rybakina, who stands 4-3 since Wimbledon, was broken five times and managed only 11 winners. Keys struck 21 winners and 16 unforced errors.
“Elena is a remarkable player who can turn a match around at any moment,” unseeded Keys said. “I needed to stay out front.
“It felt like I needed 12 match points, so I’m very happy to get the win. If you back off against her, she will run you around.
“It’s never good if she is in control, I had to take advantage of any ball I could.”
Keys followed up on her Thursday ouster of world number one Iga Swiatek and next plays the winner between Czech Petra Kvitova, a two-time Wimbledon champion, and Australia’s Ajla Tomljanovic.