Hsieh set for another upset?

It’s been a tough week for backing up big wins: Bernarda Pera (Johanna Konta), Belinda Bencic (Venus Williams), Zhang Shuai (Sloane Stephens) and Timea Babos (Coco Vandeweghe) all fell in the round after their big upsets. 

Is Hsieh Su-Wei about to buck the trend and back up her defeat of Garbiñe Muguruza with another big scalp? It’s so far so good for Hsieh, who has taken the opening set from Agnieszka Radwanska 6-2 with some unorthodox big-hitting. The amount of times she wrongfoots her opponents due to how early she takes the ball is quite something. 

The Pole has called for the trainer at the end of the set. Seems to be some knee trouble.