Petkovic was beaten by Agnieszka Radwanska in the Sydney International on Tuesday and needed to receive treatment from the trainer during that match. The 24-year-old made the last eight in last year’s Australian Open and follows former finalist Venus Williams in pulling out of this year’s tournament. The German, who was due to be 10th seed for the draw, said: “I’ve been struggling with it, but I’ve always believed it was going to be fine and so I pushed through the pain. “The last two weeks in Australia I’ve been having bigger problems; I could only play for 30-45 minutes without pain. After yesterday’s match against Agnieszka (Sydney) I decided to have an MRI and a CT and the results showed a stress fracture in my lower back. “The only thing I can do right now is rest – not walking or sitting a lot – just lying down and hoping that the bone will heal as fast as possible. “The doctors have said it will likely take me six to eight weeks to recover. I’m positive this is going to be fine, I just need to take the time off to get better. With this type of injury I’d rather take an additional week off, than start back a day early, and I need to be patient. “I’m really disappointed because I love Australia. It’s funny, I actually tore my ACL here, but on the other hand I also made my first ever Grand Slam quarter-final here (2011). “So either it’s a big high or a big low! I am so sorry that I won’t be seeing my fans in Melbourne, because I love the Australians and feel like we have a great connection.
“I’m going to head back to Germany tonight because I want to have some more tests with my doctors and be close to my family. I’m already looking forward to coming back to Australia next year.”