Australian Open preview

For Novak Djokovic, the task in 2015 is to put more space between himself and the competition.

The last calendar year of 2014 was hardly a bad one for the amiable Serb. After all, he won a second Wimbledon title and ended the campaign as the number-one-ranked man in the world. But it was the first time since 2010 that he failed to make it to the finals of at least three Grand Slam events.

That's something he'll want to improve upon, and the hard-court Australian Open, where he's won four times already in his career, would seem to be the perfect event to get the new season off to a flying start. So who might be able to stop him?

Roger Federer, for starters. The 17-time major winner and four-time Australian Open Champion was in fine form in the run-up, having recorded his 1000th match win in Brisbane. Time is certainly not on the 33-year-old's side, and his record against the 27-year-old Djokovic is basically even.

But Federer, widely regarded as the sport's greatest player, still has enough in his locker to add to his Grand Slam haul if everything falls into place.

Form is something that in short supply for Rafael Nadal at the moment. The Spaniard was forced to curtail his 2014 season because of various injuries and opened 2015 with a shock first-round defeat to world-number 128 Michael Berrer at the Qatar Open.

Although only 28, Nadal's physical and aggressive style of play has taken its toll, and despite winning the Australian Open in 2009, the tournament Down Under is the Grand Slam where he's been least successful. Still, he was a finalist in 2014 - losing to Stanislas Wawrinka - and you'd be foolish to count out a competitor as fierce as the Spanish leftie.

There's also two-time Grand Slam winner Andy Murray, from Scotland, who certainly has the sort of serve-and-volley game to give Djokovic a run for his money. Murray is a three-time runner-up in Australia so he has the credentials to progress deep into the tournament. But his record against Djokovic is a less-than-stellar: 15-8 in favor of the Serb, while Murray is coming off a disappointing 2014.

Among the dark horses is the current Australian Open champion, Wawrinka, who has shown in the past that, on a good day, he can hold his own against any of the top Tennis players. But the likelihood of anyone outside the "Big Four" taking the prize is small, and Djokovic is a clear favorite among the bookmakers.

Serena goes for number six

On the women's side, the number one seed is even further ahead of the chasing pack. Serena Williams has won five Australian Open titles and the American is coming off the back of a year when she won her 18th Grand Slam event. She has held the number one slot for more than 200 weeks.

So are there reasons to pick against her? Well, she's 33, for one thing, and has become somewhat injury prone as she gets older. Despite her five titles Down Under, she hasn't won the Australian Open since 2010.

Russia's Maria Sharapova is probably the most likely to profit if the American does falter. She won the event back in 2008, but that was the last time the number two seed won a Grand Slam on a hard surface. Still, she won her first tournament in 2015, which will aid her cause.

With last year's winner Li Na having retired from the game because of injury, the women's draw is much more difficult to predict than the men's. Victoria Azarenka won the tournament in 2012 and 2013; Petra Kvitová is a hard-hitting two-time Wimbledon champ who has perennial difficulties in Australia; Ana Ivanova is a former world-number-one who slowly but surely recovered her top-five form, and the same is true of Caroline Wozniacki.

But beating Williams to the 2015 title is a mammoth challenge for any of her current competitors.