Peterson lost the first set after tiebreak, but then came back in the match. The victory is a new scalp for the Swede, who took his first WTA title in singles in September, and is lower ranked than the Chinese - Peterson is 59th in the world, Wang Yafan 47th.
In the semi-finals, the winner now awaits between 36-ranked Julia Putintseva, Kazakhstan, and 61-ranked Tunisian Ons Jabeur.