The Swiss ace was speaking after his win over his long-time rival in the final of the Shanghai Masters on Sunday (15 October). The world number two closed the gap with Nadal at the top of the rankings by 400 points and is now 1960 points behind the world number one with three tournaments left to play.
Federer is aware that he will have to win most of the remaining tournaments and hope for Nadal to not perform as well to have a chance to finish the year as the world's top ranked player. The 36-year-old revealed that thoughts about being number one entered his mind when he was playing in Montreal, but a back injury during his final loss in Canada, which saw him miss the Cincinnati Masters, hampered his chances of fighting Nadal for the number one status.
The 19-time men's singles Grand Slam champion initially indicated that he will play the remaining three events but made it clear that winning the ATP final in London is his main priority. However, he has now put in doubt the tournaments in Basel and Paris after revealing that he could skip both or play just one before travelling to London.
"I mean, I don't even know what it takes to be honest," Federer said after his win over Nadal, as quoted by the Metro. "I just know the World Tour Finals is a must and probably Paris too and probably Basel so that all depends on how Rafa plays."
"It's a wild thought, that's why I'm not even thinking about it to be quite honest at this point. I was thinking about it going into the Montreal finals and hopefully Cincinnati and the US Open but I mean it just all didn't work out the way I was hoping – so no problem there," he explained.
'I'll just try to be healthy now, go back to the drawing board when I go back to Switzerland tomorrow with my team and we'll decide what I'm going to play – Basel, Paris – one of those tournaments or both or none – before I go to London because that's my priority right now, " Federer added.
"I want to really win the World Tour Finals and then we'll take it from there next week."