(CNN) -- Roger Federer will surrender his world No. 1 ranking to Novak Djokovic after the 17-time major winner confirmed he is pulling out of the Paris Masters through injury.
Federer endured a painful defeat to Juan Martin Del Potro at the Swiss Indoors tournament in Basel on Sunday, a match that lasted a grueling two hours and 45 minutes.
And after his marathon match, he confirmed he would skip the Paris Masters in order to focus on the season-ending ATP World Tour Finals in London that start in early November.
That decision means he will lose the rankings points he accrued from three tournaments last year, and will be unable to overhaul Djokovic even if he wins his third straight World Tour Finals crown.
"It's just too much," Federer was quoted as saying on the official Paris Masters website after defeat in his home town.
"I was trying to make up my mind and I had some niggles I didn't want to take a chance on. I don't want to take a chance for London.
"I feel very disappointed as I had one of the best weeks of my life there last year, but this is just a last-minute decision."
Djokovic enjoyed a 53-week stay at the top of the rankings after his record-breaking 2011 until Federer regained top spot after taking his seventh Wimbledon title back in July.
But Djokovic will now end the year as world No. 1 for a second successive year, the first time that has happened since Federer held it between 2004 and 2007.
With Rafael Nadal out for the rest of the year with a knee injury, Andy Murray is the major threat to the dominance of Federer and Djokovic and the Briton says he is raring to go after missing the Basel tournament.
"I had a full week of rest after Shanghai which I needed," Murray told the tournament's official website. "I've had a pretty decent preparation for the tournament, which is good."
Murray is one of the strong favorites for the Paris title, and he is gearing up for a big end to his breakthrough year in which he took his first ever grand slam victory and an Olympic gold medal to boot.
"It doesn't make sense to come and save energy," added the U.S. Open champion.
"Having a full week of rest at this stage of the season (is something that) in the past I hadn't really had, so I feel so much fresher coming into Paris than I had done the last few years.
"I'll try to play my best this week and then see what happens in London. I feel better at this stage of the year compared with last year."
Murray will begin his Paris campaign on Wednesday against either French wild-card Paul-Henri Mathieu or Spanish qualifier Ricardo Bautista-Agut.