Agnieszka Radwanska will play world number one Angelique Kerber in the WTA Finals last four after beating Karolina Pliskova 7-5 6-3.
The Polish defending champion overcame Finals debutant Pliskova in 78 minutes.
French Open champion Garbine Muguruza avoided a whitewash at the event as she beat Svetlana Kuznetsova 3-6 6-0 6-1 in their dead rubber.
Russian Kuznetsova was already through as group winner with Muguruza out after defeats in her first two matches.
Kuznetsova, who only qualified for the tournament with victory at the Kremlin Cup in Moscow on Saturday, will meet Slovak world number eight Dominika Cibulkova in Saturday’s other semi-final.
Radwanska had match point in her group-stage defeat to Kuznetsova earlier this week and the world number three looked in good form as she racked up a seventh successive straight-sets win over Czech Pliskova.
“She is playing amazing tennis this year,” Radwanska told BT Sport when asked about her meeting with Kerber.
“She has been on fire, playing unbelievable on every surface. I have nothing to lose and have to be 200% to beat her.”
The busy schedule that Kuznetsova put herself through to qualify for the event appeared to catch up with the 31-year-old as she faded badly in defeat to Muguruza.
“To go to the limit, you need to push yourself hard, but I want to do that tomorrow,” Kuznetsova said.
Article source: http://www.bbc.co.uk/sport/tennis/37800825