Doha, Qatar (SportsNetwork.com) - Former world No. 1 Jelena Jankovic upended former Wimbledon champion Petra Kvitova in Friday's quarterfinal action at the $2.44 million Qatar Open tennis event.

The fifth-seeded former U.S. Open runner-up Jankovic subdued the third-seeded Kvitova, 6-1, 6-3, on the hardcourts at Khalifa International Tennis Complex.

Jankovic's semifinal opponent on Saturday will be sixth-seeded German left- hander Angelique Kerber, who drilled Thursday's big upset winner Petra Cetkovska, 6-1, 6-0. Cetkovska stunned top-seeded Australian Open champ Li Na in the round of 16.

Also on Friday, seventh-seeded Romanian Simona Halep upended fourth-seeded former French Open runner-up Sara Errani, of Italy, 6-2, 6-0.