"I have done it in the past, and I like playing there".
Nadal, who has never won the ATP Finals, dethroned his old rival from the top of the rankings this week and will be hoping to seal the year-end spot despite injury doubts ahead of the tournament, which starts on Sunday.
There has always been hypothesis over who would step up to self-discipline Federer, Nadal and Djokovic, who agree with dominated men's tennis for 15 years. "You're playing a top-10 player every single match".
"I am very happy with the opportunity to be in this position, but I value longevity more", added number two of the ATP classification.
"We appreciate each other's games", he added.
Zverev acknowledged that Federer, Nadal and Djokovic still deserved their place at the pinnacle of the sport.
"That's a true fact because they're the ones who are winning the big tournaments but I think the young guys are improving quite quickly and it's going to be interesting to see how that goes". "I don't think it's contradictory at all".
"Everything Roger does, he does 100 per cent, so I think he's 100 per cent behind Sascha otherwise he wouldn't sign him".
The 33-year-old took to Twitter on Friday to provide an update on his fitness, stating he is "taking it day by day", after he was forced to withdraw from the Paris Masters due to an abdominal tear, though doubt remains as to whether he will be able to participate through the whole tournament in the English capital.
The Nitto ATP Finals is the final tournament of men's professional tennis season, featuring only the world's best eight qualified singles players and doubles teams as they battle it out for the last title of the season.
"At the end of the working day I assume with age and expertise I can be confident about what I do in coaching", Federer explained.
Federer has been leaking his 2020 gradually over the past few months and has already committed to play all the Grand Slams plus some other major events such as the Olympics, but now he's confirmed that he's decided not to play any tournaments in the run up to the 2020 Australian Open.
Germany's Zverev was the first of the young guns to make inroads, qualifying for the ATP Finals in 2017. So hopefully we're the ones, perchance with any other guys as successfully, with (Canada's) Denis Shapovalov now taking half in very big tennis.
The 38-year-old Swiss player holds the record for the most titles at the end-of-season event but has not won since 2011 and could see his record equalled by the Serbian this year.
"About a of the younger guys are no longer right here but however I am certain will attain very nearly as we state".