Federer won't be pushed by a towel

London - Roger Federer slapped down suggestions of playing mind games at the World Tour Finals when his choice of chair left Novak Djokovic sitting with a Federer-monogrammed towel.

Third seed Federer walked out on court first for Tuesday's group stage clash with the world number one at London's O2 Arena.

But the Swiss great's choice of chair meant Djokovic was left sitting on a bench with a blue towel reading "Roger Federer" laid out on the armrest.

The Serbian defending champion did a double-take when he saw it and briefly covered it up with a plain white towel, before raising his eyebrows and getting on with the match.

Federer said he simply went to the same chair he used in his opening group match against Tomas Berdych - and was not amused when questioned about the incident.

"A towel doesn't mean much to me. I'm not going to be pushed by a towel," he said.

"I sat on that chair when I walked out against Tomas. I said, 'I'd like to sit here again'.

"I walked out first. Usually the guy who walks out first decides which side he wants to sit on. That's the rules to me, not a towel, to be quite honest.

"Maybe to you a towel matters more. To me a towel is to take a shower with."

Federer won the clash 7-5, 6-2 to book a semi-final spot at the season-ending top eight contest. Djokovic did not detect any gamesmanship in the choice of chairs and absolved his old rival.

"I saw that. But I think you're not advised as a player when you come onto the court which bench you should take. It's completely your choice," the Serb said.

"I don't think that was his tactical approach, mess around before we even hit the first ball. I don't think that was on his mind."