Perennial world No. 1 Roger Federer finally lost his perch atop the rankings to Rafael Nadal this summer, and his quest to re-establish himself as the best tennis player in the world will begin in earnest at the 2009 Australian Open.

It’s a good opportunity for Federer to make up some points in the rankings, because earlier this year he lost to Novak Djokovic in the semifinals. That means he is only defending semifinal points, so a title Down Under would more than overcome the points that will come off the board at the end of the tournament. Nadal, however, also only made it to the semifinals, so he has a chance to increase his total as well. But the general consensus is that Federer will have an easier time of it at the Australian Open since the event is contested on hard courts. Federer has hoisted the trophy three times, while Nadal has never made it to the final. Nadal would do well just to defend his points, whereas for Federer it would be a disappointment if he did not make it past the semis.

It is also a good opportunity for Federer to distance himself from current No. 3 Djokovic, who was rapidly gaining ground on the Swiss until a late-season slump put a dent in his progress. In Shanghai, however, Djokovic has already qualified for the semifinals, so he will see a jump in his points when the new rankings come out on Monday. The Serb failed to win a single round-robin match at the 2007 Masters Cup, so he has no points to defend. Federer on the other hand, is the defending champion in Shanghai, so he needs to successfully defend the title just to maintain his point total. That does not mean, however, that Federer is unable to gain ground on Nadal. Quite the contrary! Nadal won two round-robin matches at least year’s Masters Cup, so he will lose those points since he did not attend this season’s year-end event. The Spaniard has been suffering from knee tendinitis which also forced him out of a Paris semifinal match against Nikolay Davydenko and will keep him away from his country’s Davis Cup final against Argentina later this month.

As it stands right now with the Masters Cup still in progress, Nadal leads the way with 6675 points. Djokovic is considerably closer to Federer than Federer is to Nadal at the moment. The Serb has 4645 points; Federer has 5205.

The ATP Tour is changing its points system for 2009, generally doubling the point values that were awarded this year. But that does not change the basic idea that each player needs to reach the same round of a tournament he did in the previous year in order to maintain the same amount of points relative to other players. Djokovic has 1000 points to defend from his Australian Open 2008 title. If he fails to win it again and, for example, either Nadal, Federer, or Andy Murray wins the title, Djokovic will lose ground to at least one of his main rivals.

Murray stands as the player with the most to gain heading into the Australian Open because he lost in the very first round to eventual runner-up Jo-Wilfried Tsonga this season. It’s Federer, however, who really has a chance to make a statement that he is going after No. 1.

And there’s no reason to think he won’t. Federer won three straight Australian Open championships between 2005 and 2007. He took out Marat Safin in 2004, dispatched surprising finalist Marcos Baghdatis in 2006, and defeated another surprising finalist, Fernando Gonzalez, in 2007. This season it was mononucleosis as much as Djokovic that derailed Federer’s Australian Open campaign in the semifinals. It was clear things weren’t completely right when the Swiss went to 10-8 in the fifth set with Janko Tipsarevic in the third round. Federer was not even close to the normal Federer until very late in the spring, when he started a run that included titles in Estoril and Halle and runner-up finishes in Monte-Carlo, Hamburg, Roland Garros, and at Wimbledon.

At the Australian Open 2009, Federer should be suffering no such physical problems. He is still not as dominant as he once was, but he turned his 2008 campaign around with Olympic gold in doubles and a fifth straight U.S. Open title. At the moment he is one win away from reaching the Masters Cup semifinals, but that win needs to come over Murray. After this week, Federer will have two months to rest and get his somewhat-hampered lower back (which forced him out of Paris and almost kept him out of Shanghai) in perfect shape in time for the Australian Open.

This time around it could be Nadal facing the injury questions in Australia. He will have had more than two months his rest his knee by the time the first Grand Slam of 2009 begins, but you just never know with tendinitis. Injuries are becoming a major cloud of the Spanish sensation, and while he will almost certainly be able to play Down Under, being 100 percent is a different story.

A healthy and well-rested Federer in Australia will be able to send a loud and clear message to Nadal, Djokovic, Murray, and the rest of the ATP Tour’s contenders that he is out to get back what has been rightfully his: the No. 1 ranking.

It won’t be easy, but the Australian Open will be the perfect place to start.