Angelique Kerber has helped Dominika Cibulkova reach the semi-finals of the WTA Finals.

Kerber, who had already advanced from the Red Group, beat Madison Keys 6-3 6-3 on Thursday to finish 3-0 in the round robin and eliminate her American opponent.

Cibulkova beat Simona Halep 6-3 7-6 (7-5) earlier in the day, giving her a 1-2 record.

The top-ranked Kerber will be playing in the semi-finals of the season-ending tournament for the first time after failing to advance in three previous attempts.

In 2016, the German won the Australian Open and US Open, and reached the final at Wimbledon.

In the match with Keys, half of the 18 games resulted in service breaks. Kerber broke Keys’ serve on six of seven offerings, while Keys took advantage of three of four break points.

Keys and Halep, who had her left knee taped for the match against Cibulkova, also finished the group with 1-2 records.

Svetlana Kuznetsova, who is 2-0 in the White Group, has already qualified for the semi-finals.

The second semi-final spot from that group will be decided Friday when defending champion Agnieszka Radwanska plays Karolina Pliskova.

Garbine Muguruza has already been eliminated from semi-final contention.