Ana Ivanovic a doubt for Australian Open

Former world number one Ana Ivanovic is hopeful she will be fit for the Australian Open despite being forced to pull out of the Hopman Cup on Friday because of a stomach injury.

A scan on the injury showed a grade one tear, the least serious, leaving her facing a race against time to be fit for the first grand slam event of the year, which begins on January 17.

"It's very frustrating," Ivanovic told reporters. "Hopefully I'll be fine for Melbourne but it's definitely a scare."

Ivanovic said she had been told to take complete rest for three-to-four days in order to let the tear heal, before beginning light training.

The former French Open champion said she first felt it during her singles match with Justine Henin on Thursday but that it was only when she tried to practice the next day that it really began to hurt.

"This morning, I was playing some points and on one serve I felt a sharp pain and I couldn't even hit or move after that.

"At this moment in time (my chances) are still very good because I stopped in time. I'm positive I will be fit."

The injury is a blow to Ivanovic's hopes of making a strong run in Melbourne, having battled back to the world's top 20 in the second half of 2010.

"It's very frustrating because this has been the case for a long time now," Ivanovic said of the latest in a line of niggling injury problems. "But I have to stay positive."

Ivanovic has already pulled out of next week's WTA event in Sydney and is now likely to request a late start at the Australian Open.

Her injury also cost Serbia their place in the final of the Hopman Cup because under the rules of the mixed team event, they are not allowed to bring in a replacement for the final.

Belgium, who finished second in their group, will advance in their place.

French Open champion Francesca Schiavone also suffered a groin injury playing for Italy against France on Friday but the problem is not thought to be serious.