Swiatek's US Open prep hit by early exit in Cincinnati

Madison Keys shocked Iga Swiatek to move into the Western and Southern Open quarter-finals, further disrupting the world No 1's preparations for the US Open.

Swiatek - who won her 50th match of the year in the previous round - saved four match points but was far from her best in a 6-3 6-4 loss on Thursday, as she again exited a second successive tournament event at the last-16 stage.

Keys, Cincinnati champion in 2019, had never taken a set off Poland's Swiatek in two previous meetings but the American was far more clinical with her powerful returns and groundstrokes, breaking the world No 1 five times.

"I obviously had a couple of games with a couple of match points, but I'm just so happy to be able to get the win," Keys said after her first career win over a world No 1. "The last time I played her she beat me pretty badly, so I'm pretty glad to get that one under my belt."

Swiatek had complained about the tennis balls used in the women's game in the American tournaments being different to the ones used by men, and against Keys the top seed made several unforced errors and was broken twice in the opening set.

A toilet break between sets did little to help Swiatek regain her composure as Keys put herself firmly in the driving seat as she raced to a 5-0 lead in the second set.

Serving to stay in the match, Swiatek saved two match points and that inspired her to win the next four games as Keys made several errors, but it only delayed the inevitable as Keys broke Swiatek to clinch victory with a forehand winner.

Keys will next face Wimbledon champion Elena Rybakina, who beat Alison Riske-Amritraj 6-2, 6-4 to sail into the quarter-finals, while Wimbledon runner-up and fifth seed Ons Jabeur was knocked out by Czech Petra