Muguruza, Radwanska advance to Sydney International QFs

SYDNEY (AP) Wimbledon champion Garbine Muguruza's decision to accept a wild card at the Sydney International has paid off, so far.

Muguruza, who retired in the third set from her first match at the Brisbane International last week with leg cramps, beat Kiki Bertens 6-3, 7-6 (6) on Wednesday to advance to the quarterfinals.

Leading 2-1 in the first set, she left Ken Rosewall Arena for what appeared to be a back injury. But she returned to win six of the next eight games.

''I struggled a little bit today, with my game, the conditions,'' Muguruza said.

Radwanksa advanced to the quarterfinals with a 7-6 (4), 6-0 win over qualifier Catherine Bellis.

In men's play, Paolo Lorenzi upset top-seeded Albert Ramos-Vinolas 6-3, 7-5, and Fabio Fognini defeated Alexandr Dolgopolov 3-6, 6-3, 6-4.