After her victory Serena quipped. "It was really good for me to kind of fight through that, because literally I had to fight for every point."
Azarenka said, "She played better on those important moments. I felt that every game was ad, deuce, ad, deuce. It was all about who was going to take that chance, and she took them a little better today."
Serena will face another former world number one in the form of Garbine Muguruza in the next round. Two-time Slam champion Muguruza breezed into the third round with a routine 6-1, 6-3 victory over American Lauren Davis.