Kerber or Kvitova will join other semi-finalists from White Group together with Williams – number 1 female tennis player of the world after today's game.
Agnieszka Radwanska of Poland has already made an exit from the tournament having lost all her three games.
Meanwhile in the White Group, China's Li Na is at the leading position after beating Jelena Jankovic of Serbia who is at the second place.
Victoria Azarenka of Belarus is at the third place, followed by Italia's Sara Errani.
TEB BNP Paribas WTA Championships will last until October 27.
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