Ashleigh Barty and Belinda Bencic progressed to the semi-finals at the WTA Finals in straightforward fashion on a day that could have been chaotic.
The Australian advanced first with a comfortable 6-4 6-2 win over Petra Kvitova. Then the Swiss won a tight first set 7-5 against Kiki Bertens before the Dutchwoman was forced to retire with a viral illness early in the second set.
Bencic has also enjoyed a fantastic year. She won Premier titles in Dubai and Moscow, reached her first Grand Slam semi-final at the US Open and has reached one other final, three semi-finals and a quarter-final.
While Barty has to wait until tomorrow to find out who she will play in the last four, Bencic already knows she will face Elina Svitolina, who will finish top of the Purple Group after she won both of her matches so far in straight sets.