Caroline Wozniacki beat Karolina Pliskova in the last four in Singapore last year, but it was a different story in their White Group opener.
Karolina Pliskova overpowered defending champion Caroline Wozniacki to seal a straight-sets victory on day one of the WTA Finals.
Wozniacki beat Pliskova in the semi-finals last year, but the seventh seed gained a measure of revenge with an impressive 6-2 6-4 win in their first meeting since that showdown in Singapore.
Pliskova, seemingly unhindered despite playing with a taped right calf, saved all 10 break points she faced and unleashed a barrage of powerful groundstrokes to join Elina Svitolina at the top of the White Group.
Wozniacki arrived at the season-ending tournament on a high after returning to form to take the China Open title, but the second seed now faces a battle to reach the semi-finals following a fourth loss in 10 meetings with Pliskova.
— WTA (@WTA) October 21, 2018
Pliskova grasped the initiative as the errors started to mount for the Australian Open champion, an errant forehand putting her a break down at 2-1.
Another break gave the world number eight a 4-1 advantage and she wrapped up the opening set in only 32 minutes.
Wozniacki was struggling to get her forehand going, Pliskova maintaining her momentum with a break in the opening game of the second set and consolidating with a battling hold after saving three break points.
A battling Wozniacki clenched her fist when she held to reduce the deficit to 3-2, having fended off a break point as Pliskova continued to pepper her with thunderous groundstrokes.
Wozniacki hung in there as she saved two match points before holding to trail 5-4, but Pliskova was celebrating victory following a rasping ace.
Pliskova  bt Wozniacki  6-2 6-4
Pliskova – 22/21
Wozniacki – 20/17
Pliskova – 4/1
Wozniacki – 3/3
BREAK POINTS WON
Wozniacki – 0/10
FIRST SERVE PERCENTAGE
Pliskova – 67
Wozniacki – 69
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Pliskova – 68/64
Wozniacki – 63/43
Pliskova – 73
Wozniacki – 60