Coco Vandeweghe is through to the last eight of a grand slam for the first time following a fourth-round Wimbledon win over Lucie Safarova.
Lucie Safarova's quest to reach a second successive grand slam final is over following a fourth-round defeat to Coco Vandeweghe at Wimbledon.
The Czech finished as runner-up at the French Open last month and had designs on going one better at Wimbledon after reaching the semi-finals at the All England Club last year.
However, the sixth seed was undone by a superb performance from Vandeweghe, who claimed her fourth win against a top-10 player, sealing a 7-6 (7-1) 7-6 (7-4) success on No.3 court.
Vandeweghe will now face either Maria Sharapova or Zarina Diyas in the first grand slam quarter-final of her career.
Safarova, having squandered break points earlier in the first set, struck for a 5-4 lead as Vandeweghe ballooned a backhand long.
But Vandeweghe immediately broke back and displayed the greater composure in the subsequent tie-break after both players held serve to force a shootout.
A succession of errant shots from Safarova allowed Vandeweghe to move 6-1 up in the tie-break and the American took advantage by clinching the set with an ace down the middle.
Safarova looked primed to get back into the contest when she moved 40-0 up on Vandeweghe's serve in the fourth game of the second.
But Vandeweghe displayed remarkable resiliency to save four break points and hold.
Safarova then produced a show of character of her own as she dropped serve only to instantly hit back and level at 4-4 by breaking Vandeweghe with a forehand winner.
Yet Safarova could not break Vandeweghe again and, although the second tie-break was more closely contested, the world number 47 wrapped up a stunning victory as she followed up an ace that set up match point with an unreturnable serve.