The Aussie Open is the major curtain-raiser to a new tennis year. It offers tennis fans an early indication of whether the top players are ready to protect their status or whether there might be the possibility of a little power shift at the top of the rankings.

Novak Djokovic has secured the Australian title for the last two years. In 2012 he prevailed in an epic final against Rafael Nadal, the longest Grand Slam final of the Open era. A third successive win would establish the Serbian player as a master of the blue surface and would be likely to restore him to the top of the world rankings. He had an indifferent 2012 by his standards but the Australian Open is one of his favorite tournaments and an obvious place to reassert his authority.

Nadal – ready to return?

Much will depend on the preparation and form of the medical enigma called Rafael Nadal. The Spanish player won the Australian title in 2009 and came so close to beating Djokovic in the 2012 final. Persistent and recurrent injuries have threatened to end the career of the most naturally gifted player of his generation. In the past, the Australian Open has found the Spanish star a little unfit and rusty after the winter break. If Nadal can recuperate and rediscover his fitness and form over the winter, he may be ready to announce his return in the first Grand Slam tournament of 2013.

The Past and The Future

Roger Federer and Andy Murray represent the recent past of the sport and one of its potential futures. Federer’s performances in 2012 suggested that he didn’t agree with those observers who were ready to write him off. He reclaimed his number one world ranking in a year when he was supposed to fade gracefully into the history books. Retirement might be looming, but the Swiss star obviously believes he still has the chance to add to his tally of Slams before age finally slows him down. Federer has won four Aussie Open titles, the most recent of them in 2010.

Andy Murray has been threatening to win a Grand Slam title for years. The appointment of Ivan Lendl as his coach has made a noticeable difference to his tactical approach and to his appetite for victory. The immediate reward was an Olympic gold medal. That achievement involved beating both Djokovic and Federer impressively. Murray will come back in 2013 determined to reach and win Grand Slam finals and challenge for the number one ranking.

These are the obvious challengers out to deprive Djokovic of his title. Tennis fans will hope for a fit Nadal, clement weather and another Australian Open that lives in the memory.

Stephen Craig is a part of an elite team of writers who have contributed to hundreds of blogs and news sites. Follow him @SCraigSEO.