Groth comfortably defeated Roberta Vinci of Italy 6-1, 6-2 in the quarterfinals Thursday, while her Czech doubles partner Zakopalova beat top-seeded Marion Bartoli 6-4, 6-2.
The other semifinal will be between American Bethanie Mattek-Sands and China's Peng Shuai, who both played two matches on Thursday to make up for lost time due to rain delays.
Mattek-Sands first ousted Ayumi Morita of Japan 6-3, 6-1 before overcoming Angelique Kerber of Germany 6-4, 6-4.
Peng completed a 2-6, 6-4, 6-0 victory over Olga Govortsova of Belarus before beating Sara Errani of Italy, 6-1, 6-3.
Aguero eyes Chelsea moveIsner beats Mahut - in just 90 minutes this time
