How legit is Caroline Wozniacki?

It's almost that time again -- already. Time for a new tennis season to begin. The sport doesn't waste a second, rolling back into action by the very first day of 2011. All of which means we don't have much time to look ahead at the most intriguing storylines before they've actually begun. To start turning your mind from 2010 to '11, here are five questions that will be answered as the year progresses.

1. How "real" is Caroline Wozniacki?

On the surface, you might think that Serena Williams has done the world's No. 1 player a favor by pulling out of the Australian Open and leaving her one less (major) obstacle to hurdle in her quest for her first Grand Slam. But it's as much a curse as it is a blessing. Without Serena in town, the media in Melbourne will make Wozniacki's "legitimacy" as a No. 1 player the question of the tournament as far as the women's draw goes. If she fails, yet remains No. 1, it's a question that will likely plague her well into 2011.

2. Nadal or Federer?

Despite the occasional new contender, they've remained in a class by themselves for the past five years, having won all but two Grand Slams between them during that time. Each goes into 2011 looking as strong as ever. Rafael Nadal will be trying to become the first player since Rod Laver in 1969 to own all four majors at one time, while Roger Federer finished 20-2 after the U.S. Open and ended the season with a win over his rival. Sit back and enjoy these guys one more time, since it's unlikely anyone is going to challenge their authority. As for choosing between them, that's a toss-up: Federer looked to be the sharper, fresher and hungrier player as the year ended, and I think Paul Annacone has helped inject new ideas and desire into his game. But all that must be balanced by the fact that no matter how well Federer might play, Nadal has beaten him more times than not in the most important matches.

3. How much of a factor will Justine Henin be?

Serena's comeback, or non-comeback, has overshadowed the other big return story of 2011, Henin's. She looked set to make a big impact last year when she reached the finals in Brisbane and Melbourne. But an elbow injury at Wimbledon ended her season at the halfway point. With Serena out in Australia, this is the best chance that Henin will have to make good on that promise. It might even be her last: Henin turns 29 in June. She's gotten more fragile over the years, and she can't afford any more season-ending injuries.

4. Djokovic or Murray?

Each of these two has appeared, at various times, ready to crack the Federer-Nadal stranglehold at the top. Neither has succeeded. There's no real reason to think this is the year, either. Still, Novak Djokovic will be coming in on a high after Davis Cup, even if that event and a Grand Slam are two very different animals. Andy Murray has beaten both Federer and Nadal recently, but he's also taken his share of tough losses at the hands of both. When do the close calls stop giving him confidence that he can play with the best and start making him think that when it really counts, he can't?

5. Is there a surprise in store from anyone?

You'd never get rich betting on a Frenchman to win a Grand Slam. And you would have done even worse betting on Gael Monfils each time he has shown signs of fulfilling his vast potential. But there were signs late in 2010, with his win over Federer in Bercy and his win over Janko Tipsarevic in the Davis Cup final, that he might just be pulling things together mentally. Somewhere, though, I feel like I've said that before. The Monfils saga continues, and every new story feels a little like an old one these days in tennis.