STUTTGART, Germany (AP) Top-ranked Victoria Azarenka needed nearly 3 hours to overcome big-serving wild card Mona Barthel 6-4, 6-7 (3), 7-5 on Friday for a place in the Porsche Grand Prix semifinals.

Azarenka will face fourth-seeded Agnieszka Radwanska, a 3-6, 6-2, 6-3 winner over No. 8 Li Na.

Second-ranked Maria Sharapova rallied to outlast No. 5 Sam Stosur of Australia 6-7 (5), 7-6 (5), 7-5 in a match that went a minute over 3 hours. Sharapova will face the winner of a late match between third-seeded Petra Kvitova and Angelique Kerber.