Injured Azarenka adds to Toronto withdrawals
August 5, 2013 -- Updated 1847 GMT (0247 HKT)
Victoria Azarenka takes a drink during the final of the WTA Carlsbad tournament which she lost to Samantha Stosur.
- Victoria Azarenka pulls out of WTA tournament in Toronto
- Two-time Australian Open winner has a back injury
- She lost in the final of Carlsbad tournament to Samantha Stosur
- Montreal Masters starts Monday with Novak Djokovic cefending title
(CNN) -- Australian Open champion Victoria Azarenka has joined the growing list of injury casualties at the WTA Rogers Cup tournament in Toronto.
The Belarus star has moved to second in the world rankings, despite losing to Samantha Stosur in the final of the Carlsbad tournament in California.
But after Sunday's straight sets defeat Azarenka pulled the plug on her appearance at the prestigious hard court tournament in Canada, citing a lower back injury.
"I'm so disappointed that I can't make it to Toronto as I added it to my schedule knowing what an important event it is," Azarenka said in a statement.
Azarenka on 'amazing' Australian win
Women's tennis top stars talk personal
How do you beat Serena Williams?
"I am sorry to all my Canadian fans and I will work hard to get healthy and back on the courts as soon as possible."
Azarenka had only just recovered from the knee injury which forced her out of Wimbledon after the first round.
Read: Sharapova pulls out of Rogers Cup
Maria Sharapova, who also sustained an injury in the second grand slam of the season, was an earlier withdrawal from the Toronto event.
It will leave both of them short of match practice on hard courts ahead of the final grand slam of the season at Flushing Meadows for the U.S. Open.
Britain's rising young star Laura Robson joined them on the sidelines before hitting a ball. The World No.32 pulled out ahead of a first round match against Belgian Yanina Wickmayer with a wrist injury.
Azarenka's withdrawal has meant she will be replaced in the draw by former World No.1 Caroline Wozniacki, with the Dane given a first round bye.
World No.1 Serena Williams is top seed as she builds up to her defense of the U.S. Open title later this month.
Meanwhile, the men's Montreal Masters also started Monday, with No.1 Novak Djokovic as defending champion and new Wimbledon champion Andy Murray as his main challenger.
First day action saw Germany's Florian Meyer beat Australia's Bernard Tomic 5-7 6-3 6-3 in a match between up and coming stars of the circuit.
Part of complete coverage on
April 2, 2014 -- Updated 1420 GMT (2220 HKT)
At the 2009 Australian Open, French men's tennis was the talk of the town.
April 15, 2014 -- Updated 1800 GMT (0200 HKT)
Rafael Nadal may be most at home on a clay tennis court, but he has always found comfort on the sea.
March 21, 2014 -- Updated 1107 GMT (1907 HKT)
Tennis star Venus Williams reveals how she is beating the autoimmune disease that derailed her career.
March 5, 2014 -- Updated 1014 GMT (1814 HKT)
After two decades dedicated to the game, Amelie Mauresmo wants a second life -- one away from tennis.
Almost five years to the day after reducing Roger Federer to tears at the Australian Open, Rafael Nadal shed a few in his own loser's speech.
February 2, 2014 -- Updated 0248 GMT (1048 HKT)
Li Na outperformed Maria Sharapova at the Australian Open, but can she now surpass the Russian as the world's richest female athlete?
Roger Federer may have lost again to Rafael Nadal in the business end of a grand slam, but he can take some heart from yet another record says CNN's Will Edmonds.
January 21, 2014 -- Updated 1358 GMT (2158 HKT)
Roger Federer and Stefan Edberg, Novak Djokovic and Boris Becker -- today's tennis stars are teaming up with past legends of the game.
January 15, 2014 -- Updated 1859 GMT (0259 HKT)
Can't stand the heat of the first tennis grand slam of 2014? Then you clearly haven't been doing enough Bikram yoga.
After nearly a decade without any real change at the top of men's tennis, CNN's Will Edmonds looks at next generation of future stars.
January 9, 2014 -- Updated 1314 GMT (2114 HKT)
Ana Ivanovic is still seeking to rediscover the form that took her to the top of the rankings -- but she has found a new lease of life.
January 6, 2014 -- Updated 1142 GMT (1942 HKT)
As a teen sensation, Bernard Tomic had the tennis world at his feet -- but he's in danger of blowing it, says Australian great Pat Rafter.
Today's five most popular stories