Serena Williams has come from a set down to reach the semi-finals of Wimbledon.

The five-time champion beat former World No 1 Victoria Azarenka in a hard-fought battle.

Azarenka took control of the first set, winning it 6-3. 

But Williams dug deep and won the next two sets 6-2 and 6-3.

"Yeah, it's been up and down, up and down. But somehow I'm still alive and I don't know how. We'll see what happens but I'm just happy to still be here," he said. 

She will face Maria Sharapova next - who she has not lost to since 2004 - after the Russian battled through to beat American Coco Vandeweghe.

2012 runner-up Agnieszka Radwanska will take on Garbine Muguruza in the other semi, after they beat Madison Keys and Timea Bacsinszky respectively.