Result: Caroline Wozniacki wins finale opener

Caroline Wozniacki has got her WTA Championships campaign underway with a victory over Poland's Agnieszka Radwanska this evening.

The 21-year-old did not have all her own way in Istanbul though, losing the first set 7-5.

However, Radwanska appeared to struggle with a shoulder injury and Wozniacki took full advantage to claim a 6-2 success in the second set.

The third and deciding set would proved a cagey affair, with players trading breaks of serve.

However, it was the Dane that edged through in the end to take the match 5-7 6-2 6-4.

The earlier match in the Red Group saw Petra Kvitova emerge victorious against Vera Zvonareva.