Melbourne, Nov 27 : The Australian Open tennis tournament director has tipped Andy Murray and Maria Sharapova to win the singles titles at the first Grand Slam of 2013.

World No. 1 Novak Djokovic looks to defend his crown against a likely resurgent Rafael Nadal, who is returning to the action after missing half a year with knee injury, and Roger Federer, who is looking to become the first man in the Open Era to win five Australian Open titles.

But Craig Tiley, the chief administrator at Melbourne Park, insists Murray will pose the greatest threat to the Serbian star for the Jan 14-27 event.

"I think, on the men's side Andy Murray will be difficult to beat this year," Tiley said. "Novak is a defending champion, he is playing great tennis, he is obviously tough to beat, but I think Andy Murray is someone who we are going to see even more."

Murray enjoyed the best year of his career in 2012, winning the Olympics and his first Grand Slam at the US Open in September.

In the women's draw, Tiley sided with the Russian No. 1 over Victoria Azarenka, who beat Sharapova to win the title last January.

"In the women's draw, I think, Maria," Tiley said. "I think she was probably playing the best tennis at the end of the year. Azarenka is playing great tennis and she won here last year obviously and this was her first breakthrough."

This year, players in all four main draws will fight for a share of $30 million, the biggest prize fund on the tour.  (IANS)