Jelena Jankovic has admitted that she is "really, really happy" with her victory over defending champion Petra Kvitova at Wimbledon.

The former world number caused an upset at SW19 on Saturday as she knocked out Kvitova in three sets to reach the fourth round.

Waiting for Jankovic in the last 16 will be former finalist Agnieszka Radwanska.

"I cannot stop smiling. I'm really, really happy," the Serb told reporters. "I was just happy to be playing and competing on grass. Grass is not my favourite surface and Petra plays so well on it. I think it's her favourite surface. It shows by winning two Wimbledon titles."

Jankovic, who reached the US Open final back in 2008, has never got beyond the fourth round at Wimbledon.