Former world number one Ana Ivanovic [ Images ] is doubtful for this month's Australian Open [ Images ] after suffering a stomach injury at the Hopman Cup mixed team event.

The Serb had a scan on the injury on Friday and the results showed a "significant strain", according to tournament director Paul McNamee.

With the first Grand Slam event of the year beginning on January 17, world number 17 Ivanovic now faces a race against time to be fit to play.

"It's obviously a significant strain," McNamee told reporters. "She's pretty upset."

Ivanovic is now likely to pull out of the event in Sydney [ Images ] next week but McNamee said he did not know whether she would be able to play in Melbourne [ Images ].

"It probably has implications for her, not just tomorrow (in the Hopman Cup final), but also this month."

Under the Hopman Cup rules, Serbia will not be allowed to bring in a replacement for the final, so Belgium, who finished second in their group, will advance in their place.