Roger Federer has responded to Rafael Nadal's previous suggestion that the ATP World Tour Finals could be played on clay.
The 36-year-old Swiss legend didn't even face a break point on Sunday as he opened with a straight-set win over Jack Sock in London.
Nadal, who certainly enjoys playing on clay, has vented his frustration about the court surface at the ATP Finals in years gone by.
"I believe that it’s not fair that a player like me really never played on a surface that was a little bit more favourable. I always played on the worst surface possible for me," the 31-year-old said.
"If it’s indoor at the 02, then great, but you can build a different type of surface there. It is a fantastic place to organise a World Tour Finals.
"The atmosphere is just amazing and I am very happy it is there. I enjoy it every time I have had the chance to be there, but we can play on clay there too."
Federer hits back at "silly" Nadal suggestion
Federer - making his 15th appearance at the end-of-season event - was asked about Nadal's comments following his comfortable win over Sock.
"Fair’? I’m not sure if it’s the right word," Federer said, as per Metro.
"But I think it’s right and fair that it’s indoors, as well. There is no Masters 1000s on grass. There is one Masters 1000 indoors: Paris. So I feel like indoors also deserves its place, you know.
"Could it be switched up to clay once in a while? Yeah, maybe. Could we have more 1000s on grass? Yeah, we could have that, too.
"Could we have less on clay, more on hard courts? Yes, it’s all debatable.
"I think it’s not the time of the year for clay, so there you have it. You can do indoor clay, I guess, but that’s a bit silly.
"But I get his point, and it’s a fair point."
Currently No.2 in the world, Federer is considered the favourite to win the ATP Finals but can expect to face stiff competition from his long time rival.
Nadal and Federer are the two most successful male tennis players in the sport's history, winning 35 grand slams between them.
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