Petra Kvitova was too strong and powerful for US Open favourite Garbine Muguruza as she upstaged the third seed in a straight-sets fourth-round win.
Kvitova outslugged Wimbledon champion Muguruza from the baseline in a come-from-behind 7-6 (7-3) 6-3 victory at Flushing Meadows on Sunday.
The 13th seed and two-time Wimbledon winner rallied from 4-1 down in the opening set as she ousted a wasteful Muguruza to book her spot in the quarter-finals.
Kvitova – who showed no signs of the severe hand injury she suffered during a horrific home invasion in December – will face Venus Williams in her second last-eight appearance in New York after the ninth seed prevailed against Carla Suarez Navarro.
The Czech star was slow off the mark against Muguruza following a loose start on Arthur Ashe, handing the third seed two break-point opportunities.
Muguruza only needed one chance for a 3-1 lead after a wayward Kvitova sent a forehand volley long.
The Spaniard threatened to race away with the opening set, having brought up another three break points, however, Kvitova dug herself out of a 4-1 hole by winning three consecutive games.
Muguruza managed to stop Kvitova's momentum, ending her run of three straight games by fending off a break point to make her opponent serve to stay in the set.
Kvitova's power from the baseline proved too much after she held serve before breaking again in the 11th game but the topsy-turvy set continued as Muguruza broke back immediately to force a tie-break, where the former composed herself to hit the front.
Muguruza did not wilt, breaking Kvitova in the opening game of the second set.
However, Muguruza just could not pull away from Kvitova and consolidate after the latter claimed a love break to level at 1-1.
Holding serve continued to be at a premium as Kvitova broke again to move 3-1 clear as the quarters loomed.
Kvitova never relinquished serve again, fending off three break points en route to her first last-eight appearance at a grand slam this year.