Victoria Azarenka woe extends Serena Williams's stop at the top

Victoria Azarenka has withdrawn from this week's Dubai Duty Free Championships with a foot injury. It is the second year running in which she has pulled out with an injury before her first match here.

Azarenka, who was hoping to wrest back the world No 1 ranking from Serena Williams by next weekend, suffered a bone bruise in her right heel in Doha last week. The 23-year-old Belarusian's withdrawal means Williams is guaranteed to stay at No 1 for at least the next six weeks.

"I have been playing a lot of tennis over the last five days – so going to a new tournament is too much to handle right now," Azarenka said. "It keeps getting worse."

While the women's season has been made shorter, Azarenka said the tour was still "very difficult on the body". She added: "The game has become so physical and it takes so much out of you that sometimes you just need a break. These little things just give you a warning that you have to take care of yourself."

Azarenka will also have treatment in the United States on an infected big toe which forced her to withdraw during a tournament in Brisbane last month. Azarenka, who played with painkillers last week, said that back-to-back tournaments like Doha and Dubai were particularly demanding. "You play five days in a row against the world's top players and two days later you have to start playing all those matches again," she said. "Sometimes it is too much."

Williams, who is in much the tougher half of the draw, plays her first match here today against Marion Bartoli. Petra Kvitova, who went close to beating Williams in Doha, crushed Daniela Hantuchova 6-2, 6-1 to earn a second-round meeting with Ana Ivanovic. Azarenka's withdrawal opens up the top quarter of the draw, with Italian Sara Errani, a 6-3, 4-6, 6-4 winner over the German Julia Görges, well placed.