Djoko, Wawrinka and Muguruza all battling to make the Aussie Open
Novak Djokovic, Garbine Muguruza and Stan Wawrinka all face fitness questions ahead of next week's Australian Open.
Both Djokovic and Wawrinka have not played a competitive match since Wimbledon of last year and have spent the last six months in recovery.
The former World No.1 made an impressive return to action in an exhibition clash with Dominic Thiem yesterday but admitted his elbow is still not 100 per cent.
Doubt was cast over whether Djokovic would be fit to play in the Australian Open, which starts on Monday, when he withdrew from warm-up events in Abu Dhabi and Doha.
But, after beating Thiem 6-1 6-4 at the Kooyong Classic, Djokovic declared himself happy.
He said: "I don't want to be overconfident. I'm happy with the way it went today. But I don't want to say it's 100 per cent."
Wawrinka's own attempts to prove his fitness have not proved so fruitful. The Swiss, who underwent knee surgery in the wake of his Wimbledon exit, pulled out of an exhibition event yesterday.
Muguruza's preparations have been similarly thrown into disarray after she was forced to withdraw from the Sydney International with a leg injury.
Hours after battling past Kiki Bertens 6-3 7-6 (6) to reach the quarter-finals, the 24-year-old announced she had withdrawn.
She said: "I have pain in my right adductor. During the match the pain has been there."