"We always have great matches - the last two times we've played I've lost to her," said Wozniacki afterwards.
She was on impressive form throughout, showing quick thinking and movement to outsmart her good friend.
? WTA (@WTA) February 16, 2017
This was the 16th time the pair had faced off, with the Dane now 10-6 up in the head-to-head.
The World No.18 now faces qualifier Lauren Davis in the quarterfinals, and knows that she will be tested by a player high on confidence.
"She's a great player, she's very fast, strong forehand, running very well - she's a tough opponent," Wozniacki said. "I'm excited for it."