Fans of Novak Djokovic have been left bewildered after the Serb's name was left out of a tweet from the Australian Open's official account.The tweet, published on their verified account, was promoting the scheduled 2018 event, which kicks-off in January in Melbourne.The names of tennis superstars Rafael Nadal, Roger Federer, Andy Murray, Serena and Venus Williams, along with Simona Halep, were all published by the organisation in the promotion message which was posted online.However, one name was surprisingly absent, with Djokovic not included in the post which read: "The World's best will be back in Melbourne for #AusOpen 2018."The 30-year-old has enjoyed previous success at the tournament Down Under, and has won six Australian Open titles.Indeed, Djokovic has won 12 Grand Slams in a trophy-laden career, and in 2015, he became the first tennis player on the tour to win £20m worth of prize money throughout the course of a season. 2017 has been a troublesome year for Djokovic, however, who has been beleaguered with injury and fitness issues throughout the course of this calendar year.In July, he announced that an elbow injury sustained prior to the start of the US Open would subsequently keep him out of action until the New Year, meaning that he will miss the ATP Finals season ending event, which commences at the 02 Arena in November.Check the tweets out below.

Despite his fitness battle and frustration, Djokovic, as well as world number one Murray, will be ready for the tournament in Australia, according to Craig Tiley, a managing director of the competition.

Tiley said: "On the men's side, there has been a lot of concern and conjecture around Andy Murray, Novak Djokovic, Kei Nishikori.

"I can tell you that in talking to Andy, he has been training and he is preparing for having a great year in 2018.

"How much would this year have hurt him, to watch over the entire year Roger and Rafa share four grand slam titles - he would not have like that."