Petra Kvitova knocked out reigning champion Agnieszka Radwanska to reach the semi-finals of the WTA Dubai Tennis Championships.
The sixth seed recorded her first win over a top-five player in the rankings since 2011, triumphing 6-2 6-4 despite her Polish opponent producing just five unforced errors.
Kvitova's aggressive approach - she hit 37 winners but also had 38 unforced errors - paid off; she broke four times in winning the first set and then edged 4-2 in front at a crucial stage in the second.
"I'm glad I can be here and I've played three great matches so far," she said afterwards. "It can help me for the rest of the season."
Next up for the former Wimbledon winner will be Caroline Wozniacki in a battle between the two players who ended 2011 at the top of the rankings.
Wozniacki - the eighth seed - came through a gruelling three-setter with Frenchwoman Marion Bartoli, eventually triumphing 4-6 6-1 6-4.
The Dane was warned for illegal coaching as the quarter-final boiled up to a thrilling finish, apparently because she was talking to her father Piotr.
"I was telling him what I was doing wrong," she revealed afterwards. "There's not much he can say because he knows that if he says yes, then he's in trouble, and if he says no, he's in trouble too."
The other half of the draw will see top-ranked doubles pairing Roberta Vinci and Sara Errani put their friendship on hold to go head-to-head for a place in the final.
Having already accounted for Angelique Kerber, Vinci beat former US Open champion Samantha Stosur 6-2, 6-4. It is the first time the Italian has beaten two top-10 players in the same event.
Now she faces a familiar face in Errani, who overcame a disastrous second set to knock out Russian Nadia Petrova 6-4 0-6 6-3.
"Normally she's with me on my side of the net and not on the other one, so to see her on the other side is tough because one of us will lose," Errani said on the WTA Tour's official website.
"She's an amazing person outside the court. Outside the court she will always try to help you when she can. She's like a sister to me. We stay together maybe 300 days a year. Of course we have had a lot of good moments together."