Pakistan, Aug. 21 -- World number one Aryna Sabalenka's preparations for her US Open title defence suffered a setback when she lost to Sara Bejlek at the Cincinnati Open on Wednesday, while Tommy Paul saved a match point to knock out top seed Alexander Zverev.

Czech Bejlek claimed the biggest win of her career with a 7-6(7) 6-4 victory over Sabalenka in the round of 16, rallying from 5-1 down in a first-set tiebreak and 4-1 behind in the second set to secure her first win over a top-10 opponent. The 20-year-old wrapped up the contest in about two hours and will next face Madison Keys in the quarter-finals. Sabalenka's defeat means Elena Rybakina can replace her as world number one by reaching the Cincinnati final.

In the men's draw, Ame...