The Swiss star lost to Andy Murray, Rafael Nadal and Novak Djokovic early last year before recovering to reach the final in all four Grand Slam events, winning his first French Open and then Wimbledon for his 15th major title to surpass Pete Sampras' record.
In the first month of 2009, Federer lost to Murray in Doha and Nadal in the Australian Open final, before pulling out injured from a Davis Cup series against the United States in February. In March, Djokovic beat Federer in the Miami semifinals.
"Last year, I had problem at the start of the season with my back," Federer said Sunday. "I lost to Murray, Djokovic and Rafa, who got the better of me at the start of the season. But I feel fine now because I have been practicing enough to feel confident of winning."
Federer's Roland Garros victory gave him a career Grand Slam, while the Wimbledon win helped take the No. 1 ranking from Nadal. He then reached the U.S. Open final, only to lose to Juan Martin Del Potro of Argentina, but ended the season with four titles.
"I got better and better as the season went on," Federer said. "I was able to bounce back and was on a roll. (Winning in) Paris and Wimbledon showed that I was unbeatable. I can do it again. That's a good feeling to have, that I can do it again."
The Qatar Open starts Monday and Federer, a two-time champion, will meet Christophe Rochus of Belgium in his first match. He is drawn to play sixth-ranked Nikolay Davdyenko of Russia, who won the season-ending London World Tour Finals in November, in the quarterfinals.
"It is hard to be competing against the best, but I know I can win more tournaments this year," said Federer, who finished third Saturday in the season-opening Capitala exhibition tournament in Abu Dhabi, United Arab Emirates.
"I have been practicing good. The end season was short, so I feel my game is where it is supposed to be. I know I can make a few adjustments to my game and play well again."
Nadal, who leads 13-7 over Federer in their head-to-head record, won the Abu Dhabi exhibition final by ending a two-match losing run to Robin Soderling. The Swede beat Nadal at the 2009 French Open, where the Spaniard had been unbeaten since 2005.
"I got three matches in Abu Dhabi. I felt good on court. I was moving well on the court," Nadal said.
Nadal had chronic injuries to both knees and an abdominal complaint last season, forcing him to miss Wimbledon. Asked about his condition, the Spaniard replied: "I am OK. I feel fine. I just want to play my best tennis in every match I play. That's my goal."
The 10th-ranked Jo-Wilfried Tsonga of France withdrew Friday from the event because of a wrist injury.
Soderling, Ferrer advance in Abu DhabiZaragoza sack Marcelino
