The ATP's season-ending tournament for the world's top eight players looks wide open ahead of its start Sunday.
Then again, it seems that just about every time questions arise, Federer has the answer.
Last year, people were wondering if the Swiss star's game was starting to slip after he lost two matches in a row for the first time in 4-1/2 years, including the opening round in Shanghai. Federer won his next four matches in dominating fashion to take his fourth Masters Cup crown.
This year the questions returned as he battled the mononucleosis virus, failed to add to his Grand Slam total in the first three majors of the season and saw Nadal finally rise from the second ranking and end Federer's record 237-week reign at the top of men's tennis.
Then Federer went out and won his fifth consecutive U.S. Open to pull within one of Pete Sampras' record of 14 Grand Slam titles - a standard he will try to match at the Australian Open in January.
Certainly, having Nadal out - tendinitis in his right knee caused him to default in Paris last week and could keep him out of the Davis Cup final later this month - would appear to ease Federer's challenge here.
But Federer has been nursing a sore back that forced him to withdraw in Paris too. And while the newcomers will be learning their way around Shanghai, they look hungry.
Second-seeded Novak Djokovic of Serbia, who has been trying to break the Federer-Nadal stranglehold on the top two spots in the rankings, gets the competition started Sunday against Juan Martin Del Potro. The Argentine has jumped from No. 50 to No. 8 this year, winning four straight titles and compiling a 23-match winning streak that Andy Murray ended in the U.S. Open quarterfinals.
While Djokovic earned his first Slam this year, in Australia, he appears to be staggering toward the end of the year as he did in 2007, when he complained he was worn down by a heavy schedule. The Serb lost in the round of 16 in his past two tournaments and has won only two of his past four matches, both times when his opponents retired with injuries.
Also on Sunday's schedule for the Blue Group will be Russia's Nikolay Davydenko against Jo-Wilfried Tsonga. The Frenchman had to win in Paris to seal his spot in Shanghai and has jumped from No. 38 to seventh in the rankings despite sitting out three months while recovering from knee surgery.
Federer gets into action Monday in the Red Group against France's Gilles Simon, who was added to the field after Nadal's withdrawal.
Murray, who has been living up to his long-touted potential with a 14-match winning streak that was ended in Paris by David Nalbandian, plays American Andy Roddick in the other Red Group match.
Murray, Simon, Tsonga and del Potro are playing in the Masters Cup for the first time.
The Masters Cup winner will take home $600,000 and could make it $1.3 million by going through the tournament undefeated.
This is the last year that the competition will be held in Shanghai; it moves to London in 2009.
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