The Dane, who is one of five players who could finish the year as world number one by winning the tournament, broke her opponent five times in a 6-0, 6-2 win.
The win secures her passage into the semi finals from Red Group and she will face Caroline Garcia, who beat Elina Svitolina 6-7 (9-7), 6-3, 7-5, in the final group game on Friday.
“Even if you lose the first match, you still have nothing to lose,” Wozniacki said after the win. “It’s just a nice cushion to have. I think that kind of motivates me to start off strong and just go for it.
“I just ran a lot of balls down and I played aggressive and I mixed up the pace. Everything I wanted to do was going my way.”
As aforementioned, Caroline Garcia won a marathon match against Elina Svitolina, prevailing 6-7, 6-3, 7-5 after 2 hours and 44 minutes. The French player beat Svitolina for the second time this month.
Garcia hit 58 winners and 31 unforced errors, while Svitolina recorded 33 winners and 22 unforced errors.
As things stand, any one of Halep, Garcia or Svitolina could join Wozniacki in the semi-finals depending on the results of Friday’s last robin-round matches.