Top seed Serena Williams is through to the semi-final of the 2013 WTA Tour Championship following her victory over Petra Kvitova on Thursday.
The 32-year-old American demolished fifth seed Kvitova 6-2, 6-3 to make it 3/3 wins in the Red Group in the season-ending tournament holding in Istanbul, Turkey.
Angelique Kerber beat Agnieszka Radwanska 6-2, 6-2 to keep her hope of reaching the semis alive.
Germany’s Kerber will face Kvitova in the only remaining match of the Red Group with a last four slot up for grab for the winner.
China’s Li Na leads the White Group after overcoming Jelena Jankovic 6-3, 2-6, 6-3 in the first three-set match of the ongoing tournament at the Sinan Erdem Dome.
The Chinese lady’s victory is her second victory in the group, while Jankovic, who is due to face Italy’s Sara Errani in her last group match, has won and lost one match apiece.
Li will meet Victoria Azarenka, who also has a 2/1 win record, in her last group match.
Polish third seed Radwanska is out of the tournament, which features eight of the top nine in the WTA rankings, with the world number three absent due to injury.Radwanska could only manage a 3/0 win record.