Rafael Nadal will finish the year as world number one after Roger Federer was ruled out of the Paris Masters.

Federer had been chasing Nadal and moved a step closer with victory at the Swiss indoors in his hometown of Basle on Sunday with victory over Juan Martin Del Potro in the Basel final, but a back injury has jolted to his hopes of overhauling the Spaniard in the ATP standings.

Despite reducing Nadal’s lead at the top to 1,460 points, it now appears Federer   focus will be on the ATP finals in London.