Angelique Kerber has eased into the last four of the WTA tennis Finals with an unbeaten record when the world number one thrashed Madison Keys 6-3 6-3 in the Red Group finale in Singapore.
The 28-year-old German won all three of her round robin matches and her straight sets triumph over Keys ensured Dominika Cibulkova would join her in the semi-finals after the Slovak had earlier ground out a 6-3 7-6(5) victory over Simona Halep.
Kerber has enjoyed a breakout season with grand slam victories at the Australian and U.S. Opens, and her baseline hustling and resilient defence proved far too strong for an erratic Keys, who was broken six times in nine service games.
"It's always tough to play against Madison so I was focused on playing my best and going for it when I had the chance," Kerber said. "I moved and returned well and it feels incredible to be in the semi-finals for a first time."
Kerber will face either defending champion Agnieszka Radwanska or Karolina Pliskova, a rematch of last month's U.S. Open final, in Saturday's semi-finals while Cibulkova is set for a showdown against White Group winner Svetlana Kuznetsova.