Dominika Cilbulkova fought from a set down to beat Agnieszka Radwanska 3-6 7-6 6-3, sealing a place in the semi-finals at the Miami Masters.
The third seed looked in control early on, clinching an early break to wrap up the first set, while Cibulkova made a series of double faults.
However, the Slovakian cut out the errors in the second to take Radwanska to a tie-break, before edging out the Polish player to tie the match.
Momentum appeared to be with the Australian Open finalist as she claimed the opening two games of the decider, but Radwanska quickly broke back to get the third back on serve.
The 10th seed had to remain patient for another chance to break her opponent, but she was able to take the lead again in the eighth game to give her the chance to serve for the match.
Cilbulkova had to save four break points as her opponent fought hard to stay in the match, but she eventually brought up a match point before wrapping up the contest after almost two hours and 40 minutes.
Cibulkove will face either Li Na or Carolina Wozniacki in the last four.
Sian Cowper
