Novak Djokovic is guaranteed to overtake Roger Federer in the rankings and finish 2012 as world number one.
The Serb lost his top ranking to Federer after the 31-year-old Swiss player
But Federer will not defend his
Paris Masters title,
after which Djokovic will return to number one.
His absence means Djokovic will take an unassailable rankings lead ahead of the season-ending ATP World Tour Finals on 5 November.
ATP world rankings
(Switzerland), 12,315 points
The 25-year-old will be the first player to top the men's singles rankings at the end of consecutive seasons since Federer did it from 2004 to 2007.
Djokovic won three Grand Slam titles in 2011 and began the year by
retaining his Australian Open crown
He lost the
French Open final
to Rafael Nadal, reached the
semi-finals at Wimbledon
and was beaten by Briton Andy Murray in the
US Open final.
Djokovic has spent 53 weeks as world number one. Seven-time Wimbledon champion Federer holds the record of 301 weeks at the top, having surpassed Pete Sampras' previous best of 286 in July.