CINCINNATI: World number one Aryna Sabalenka was sent spinning out of the fourth round of the ATP-WTA Cincinnati Masters, beaten 7-6 (9/7), 6-4 by 35th-ranked Czech Sara Bejlek.

Sabalenka, who had cruised through the previous round, was ambushed by the 20-year-old, whose movement left the top seed searching for answers in a Wednesday night contest completed shortly after the clock ticked past midnight into Thursday morning.

Sabalenka was up a break in the 65-minute opening set and then led 5-1 in the tiebreaker before Bejlek roared back.

Bejlek broke the Belarusian star three times in the second set and secured the win with a love service game capped by an ace.

“I lost my words — it feels incredible,” Bejlek said after making her first win over a top-10 player a triumph over the No. 1.