Roger Federer has won one title over the past 14 months, at a low-key tournament this summer. The ATP Finals in London are his last chance to collect another title.
"I still have another week where I have to give it all. After, it will be long holidays," said the 32-year-old Federer after losing to Novak Djokovic 4-6, 6-3, 6-2 in their first meeting this year in the Paris Masters semifinals on Saturday.
The pair was placed in the same group at the season-ending, eight-man finals, which start on Monday.
The draw Saturday placed top-ranked Rafael Nadal in Group A alongside fellow Spaniard David Ferrer, Tomas Berdych and Stanislas Wawrinka. Nadal lost to Ferrer in the semifinals in Paris and will have another chance when he plays him again in London on Tuesday.
The finals have a round-robin format, with the top two finishers reaching the semifinals.
Berdych and Wawrinka will open on Monday, followed by del Potro playing Gasquet. Wimbledon champion Andy Murray pulled out after having back surgery.
Djokovic won his 16th straight match in Paris in the win against Federer. He is the defending champion in London, where he beat Federer in the final last year. Djokovic also won the title in 2008, while Federer has won it a record six times.
Federer and Djokovic, who faced off for the 30th time, will be playing in a tough Group B that also includes Juan Martin del Potro and Richard Gasquet.
Federer said he will focus on his recovery ahead of Tuesday's match against Djokovic.
"I'm always excited about those challenges," said Federer, who will be competing for the 12th straight year in the ATP Finals. "I have had a good couple of weeks now, and the most important thing is to recover as much as I can. So maybe the extra day I will get over Novak now, who knows, could be an advantage. But I doubt it."
Federer, who won his last Grand Slam title at Wimbledon in 2012, has only two victories against top-10 opponents in 2013. He registered the first one in January against then-No. 8 Jo-Wilfried Tsonga in the Australian Open quarterfinals before a series of defeats against opponents outside the top 50. He confirmed his recent improvements with a win over del Potro in Paris this week.
After reaching the final in Basel for his first final in more than four months in October, Federer showed more signs of recovery in Paris, where the back problems hampering him for most of the season did not reappear.
"I played a lot of tennis during the past 10 or 12 days. It gave me a lot of information," Federer said. "I know what I have to do now. I know what I did well, what I can improve. I know physically where I am, and mentally I have a lot of confidence. I know my body is keeping it up."
