After withdrawing from the Tie Break Tens event in Melbourne, Stanislas Wawrinka could potentially miss the Australian Open. The 32-year-old cited a shoulder injury as his main reason for withdrawing.

The 10-point competition was scheduled to be Wawrinka's return from two knee surgeries that have kept him off the court for more than six months. Even before that, Wawrinka had withdrawn from the Abu Dhabi exhibition and scheduled no ATP events before the Australian Open.

While still in the lineup, Wawrinka noted that he would have to be confident in his fitness before he decided to play the Australian.

"I cannot do everything yet but I’m happy with the way I’m practicing so far," Wawrinka had said. "I know it’s gonna take more time to be 100 percent but as long as my knee is doing well, that’s the most important.

"When you play a match it’s different to practice. You also add the stress, you also start to be more tight in the movement. So, for sure, I will play only if I have zero risk."

Both Rafael Nadal and Novak Djokovic played the Tie Break Tens and Kooyong exhibitions as scheduled, their first appearances of the season. Djokovic had also been sidelined since Wimbledon, and withdrew from Abu Dhabi and Doha with his elbow injury.

Wawrinka is No. 9 in the rankings.