Federer, who needs one more Grand Slam title to equal the career record of 14 by Pete Sampras, has won the title in Doha twice, in 2005 and '06. This year, he will face Potito Starace of Italy and could meet Andy Murray in the semifinals.
"One of my goals this year is to regain the top ranking,'' said Federer, who beat Murray in the U.S. Open final for his only Grand Slam title of 2008 but lost to the Briton on Friday at an exhibition tournament in the United Arab Emirates.
Nadal won both the French Open and Wimbledon last season before taking gold at the Beijing Olympics. But he lost to Murray on Sunday in the final of the Capitala World Tennis Championship.
In Doha, Nadal will open against Fabrice Santoro of France.
"Happy New Year,'' Santoro said after the draw. "Obviously it will be tough for me. It is not an easy match to start the new season against a player like Nadal. But I will also try to make it difficult for him.''
Nadal also has Andy Roddick and Gael Monfils in his half of the draw.
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