Petra Cetkovska has eliminated Caroline Wozniacki from a grand slam for the second time in her career, with the Czech prevailing in a thriller at Arthur Ashe Stadium.
Cetkovska stuttered in the second set to let the fourth seed back into the contest on Thursday but in a tense third set, the 30-year-old survived four match points to triumph 6-4 5-7 7-6 (7-1) at the US Open.
It was a case of d j vu for the pair, with Cetkovska having stunned Wozniacki in the second round at Wimbledon in 2013.
Cetkovska faced three match points on her serve in the 12th game of the third set after 11 straight holds from the duo, but the world number 149 showed tremendous character to hold and force a tie-break, which she dominated.
Italian 26th seed Flavia Pennetta awaits Cetkovska in the third round at Flushing Meadows.
In a frustrating match for Wozniacki, the Dane stalled in the first set after surging to 3-0 lead.
Cetkovska won six of the next seven games, including three straight on the 25-year-old’s serve to take the set in 43 minutes.
Wozniacki trailed 3-0 and 4-1 in the second set to appear on the brink of a straight-sets loss.
But Cetkovska was unable to make the most of the opportunity in a set that included seven breaks of serve; with the Czech double-faulting twice in the 12th game to hand Wozniacki a break and the set.
After the struggles on serve in the second set, the third set featured 12 consecutive holds but Cetkovska signalled her intentions in the tie-break, coming to the net on the opening point when returning to hit a winner.
Wozniacki failed to win a point on her serve throughout the tie-break as Cetkovska swarmed around the court, with the latter moving 5-1 ahead with a backhand down the line after a net cord left her scrambling.
It left her opponent frustrated and effectively finished as Cetkovska sealed a surprise win.