SINGAPORE - The Red Group semi-finalists for the BNP Paribas WTA Finals Singapore presented by SC Global are set, with world No. 1 Angelique Kerber on top and No. 8 Dominika Cibulkova second.

Kerber qualified first, after Cibulkova's 6-3, 7-6 (7-5) win over Romania's Simona Halep on Thursday afternoon (Oct 27).

For the Slovak to reach the last four, she needed Kerber to beat Keys in straight sets, and the German returned the favour in the evening with a 6-3, 6-3 victory over the American.

Both had exchanged breaks of serve early in the match. A Kerber forehand down the line handed the German the fifth break of the set and a 4-3 lead, and she broke Keys again to take the set 6-3.

Although Keys broke serve to start the second set, a slew of unforced errors from the world No. 7 and steady hitting from Kerber saw the set go the same way as the first.

Kerber is undefeated in the group stage of this year's tournament, and it is her first semi-final appearance in four attempts at the US$7 million (S$9.8 million) event.

Addressing the crowd after the match at the Singapore Indoor Stadium, the 28-year-old said: "I was moving very well and getting all the balls back; my returning was good as well and I think I played a good match - it was good tennis from both of us.

"I have some great memories here from last year ... it's so good to be into the semi-finals for the first time, so thank you, guys."