Caroline Wozniacki produced an almost perfect display to thrash world number one Simona Halep 6-0 6-2 in 63 minutes to book her place in the semi-finals of the WTA Finals.
The former World No 1 broke three times in a near perfect first set, in which she served at 94 percent and made just two unforced errors winning the first set in 23 minutes.
Halep now lives to fight another day after her opening straight sets victory over Caroline Garcia gives her a 1-1 record in the Red Group.
Wozniacki has been the form player on the WTA Tour this season, winning 58 matches, reaching seven finals and claiming one tournament victory in Tokyo last month, and she has retained that consistency in both her wins in Singapore.
With Wozniacki having secured her place in the last four following a crushing win over Halep earlier, both debutants Elina Svitolina and Caroline Garcia had a topsy turvy encounter. The Frenchwoman staged a great comeback to win 6-7 (7/9) 6-3 7-5 and secure a debut victory.
Garcia must beat Wozniacki and will need Svitolina to beat Halep to progress, while Svitolina will have to rely on beating Halep in straight sets and Wozniacki beating Garcia. If Halep beats Svitolina, she will join Wozniacki in the last four no matter how Garcia fares against Wozniacki.
Karolina Pliskova has already qualified from the White Group, with Garbine Muguruza and Venus Williams playing for the second qualifying spot on Thursday.