Former Swedish tennis star Mats Wilander says he doubts Switzerland's Roger Federer will ever reclaim the world No.1 spot from Spanish rival Rafael Nadal.
"I do not believe Federer will be world number one again," Wilander told Saturday's edition of German daily Sueddeutsche Zeitung.
"That is due to the way the ATP rankings are calculated, because you have to be powerful week after week.
"If Federer wants to be world number one again, he will have to win lots of small tournaments and I don't believe that interests him.
"What he is interested in doing is winning the grand slam tournaments and beating Nadal," added the Swede, who won seven grand slam titles in his career.
Having won Roland Garros and Wimbledon this year, Nadal officially became world No.1 on August 18 this year, ending Federer's 237-week run at the top of the ATP rankings.
With both Nadal and Federer having reached the US Open semi-finals in New York, Wilander, 44, says the hard-court surface of the Arthur Ashe Stadium is the Swiss star's best chance to beat clay-court king Nadal.
"It is on this surface that the play of Nadal is most readable," added Wilander.
