Victoria Azarenka pulls out of the Dubai Duty Free Championships

Victoria Azarenka has won all her 17 matches this year, but the season is already taking its toll on the new world No 1. Having injured an ankle en route to winning the Qatar Open last weekend, the Australian Open champion today pulled out of the Dubai Duty Free Championships here just hours before she was due to play her first match, against Julia Goerges.

"It's just too much of a risk," Azarenka said. "It was already hurting in the semi-final last week. In the final I tried to do everything to be able to play. I took a lot of painkillers, but apparently it didn't get better. I had to adjust my movement and compromise in other parts of my body, which started to hurt."

Azarenka, who expects to return in Indian Wells next month, is the fourth top 10 player to pull out of the tournament this week through illness or injury following the withdrawals of Petra Kvitova, Li Na and Vera Zvonareva. Dominika Cibulkova, the world No 16, also retired mid-match with a hamstring injury.

"The game has become so physical," Azarenka said. "Sometimes it's really tough on the body to play week after week. For example, these tournaments back to back, with such a tough field, it takes a lot out of you physically. It's just tough."

Agnieszka Radwanska, who reached the quarter-finals with a 7-5, 6-4 victory over Israel's Shahar Peer, believes that one of the reasons for the current spate of injuries is that some players work too hard over the winter.

"Sometimes in the off-season the girls are doing too much," Radwanska said. "You think you have two months off and can work hard, but then suddenly you have some tough matches at the beginning of the year and it's too much for the body. In the head everything is fine, but for the body it's not. You cannot really cheat the body. If it's painful, it's painful."

Sabine Lisicki, another quarter-finalist thanks to a 6-3, 6-3 victory over Iveta Benesova, agreed. "I think the problem is that the season is from January until November," she said. "You still want to improve so you're practising a lot and pushing your body. I think it's also a very fine line to see how much you can do off the court, still be fit, and not to do too much to get injured."

With so many top players falling by the wayside, organisers were no doubt relieved that Caroline Wozniacki safely negotiated her passage into the quarter-finals. The 21-year-old Dane, who lost her world No 1 ranking to Azarenka last month and suffered a surprise early defeat to Lucie Safarova in Doha last week, beat Romania's Simona Halep 6-2, 6-3. Wozniacki now plays Ana Ivanovic, who beat Maria Kirilenko 6-2, 7-6.