Ana Ivanovic faces a race against time to be fit for the Australian Open after she was forced to withdraw from the Hopman Cup, leaving Belgium to take Serbia's place in the final.

The former world No. 1 suffered an abdominal injury during her singles rubber against Justine Henin on Thursday and, although she soldiered through the mixed doubles alongside Novak Djokovic, the problem has been aggravated.

18995 - Ivanovic withdrawal gifts Belgium a place in the f

The 23-year-old held a short practice session on Friday morning but her discomfort was obvious as she cut it short, with scans later confirming a significant strain.

Under Hopman Cup rules, substitutes are not permitted, meaning Belgium were promoted to the final as group runners-up. They will play either France or USA in the showpiece, with the American team one win away from topping the group.