The Wimbledon champion, Garbiñe Muguruza, withdraws from the Sydney tournament due to a leg injury. It is her second consecutive withdrawal at the start of the season.
The Spaniard, who retired in the third set of her first match at the Brisbane tournament last week due to leg cramps, had defeated the Dutch player Kiki Bertens 6-3, 7-6(6) to advance to the quarterfinals.
But a thigh injury on her right leg forced Muguruza to withdraw from her next match, giving a direct ticket to the semifinals to her intended opponent, Australian Daria Gavrilova, who had defeated her compatriot Sam Stosur 6-4, 6-2.
"I'm disappointed, but I've spoken with the WTA doctors and my team after the match, and following their recommendation, I have to withdraw from the tournament," Muguruza said. "I have pain in my right adductor since I started training here. During the match, the pain has been there all the time, but I wanted to compete."
After four days of the tournament, Muguruza was the only seeded player left in the women's draw following the defeat of the second seed, Venus Williams, on the eve.
Agnieszka Radwanksa advanced to the quarterfinals after defeating American Catherine Bellis 7-6(4), 6-0. The Polish player will face the Italian Camila Giorgi, who eliminated Czech Petra Kvitova, a two-time Wimbledon champion, by 7-6(7), 6-2.
This is the fourth time that 28-year-old Radwanksa has reached the semifinals in Sydney.
In the men's draw, Paolo Lorenzi defeated the top seed Albert Ramos-Vinolas 6-3, 7-5, and Fabio Fognini defeated Alexandr Dolgopolov 3-6, 6-3, 6-4.
In other second-round matches, Daniil Medvedev beat Jared Donaldson 6-3, 4-6, 7-5, Benoit Paire defeated Leonardo Mayer 6-2, 3-6, 6-1, and the fifth seed, Adrian Mannarino, overcame Ricardas Berankis 6-2, 6-1.