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.