Marin Cilic, who withdrew from the Brisbane International, may also not play the Australian Open. The U.S. Open champion has been experiencing shoulder problems and says he will try to play the first Grand Slam of the season, which begins on January 19, but he may not be able to.

“I already have had my shoulder from the past five or six months,” he told the Croatian newspaper HRT. “I need to take a break, but I do not know if if is two weeks or four weeks, how long it’s going to last. I'm going to do my best to get to the the Australian Open.”

Interestingly, Cilic said that he wasn't 100 percent during the ATP World Tour Finals, in which he lost in all three matches. He then decided to play the International Tennis Premier League two weeks ago, for the UAE Royals team. He was said to have been paid a lot of money for his appearance and did turn up to play, although the Croatian did eventually pull out because of his right wrist.

The Brisbane event, despite Cilic's withdrawal, features a men's line-up which contains Roger Federer, Kei Nishikori, Juan Martin del Potro, Milos Raonic, and Grigor Dimitrov.