"It's the last step so if you do well you end up on the big tour".
In the ATP Finals opener on Sunday, South African Kevin Anderson beat Austria's Dominic Thiem 6-3 7-6 (12-10) in the "Lleyton Hewitt" group, which also boasts Federer and Kei Nishikori.
Contrary to popular perception, the Swiss is not the king of London, but he has won two of his four World Tour Finals trophies here, most recently in 2011, and needs one more triumph to reach a considerable landmark: a century of tournament wins.
But it is hard to see anybody other than Federer or Djokovic prevailing.
They shared the stage for one of the most memorable matches of the season when Anderson defeated Isner 26-24 in the fifth set of a six-hour-plus semi-final that directly led to Wimbledon announcing the introduction of final-set tie-breaks.
Unsurprisingly, Federer is a heavy favourite, with the Exchange now pricing the Swiss legend at [1.29], although I think this is a little short. This year, Federer won the Australian Open, Nadal won the French Open, while Djokovic won Wimbledon and the US Open.
"It's extra special this season because of the whole journey I've been through the past 15 months, particularly the last eight months, after surgery in February".
"I'm very happy I won a Slam and very happy I played as well as I did throughout the season".
"It's not because of London and not because of anything to do with this event which is a great success here at the O2 Arena".
Djokovic is the overwhelming favourite to win the title, however, Federer, as he showed in the semifinal loss against the Serb in Paris a week ago, will go in all guns blazing in search of his 100th title.
Tennis has been marred by players haranguing ball boys and girls for towels in recent years and a trial at the Next Gen Finals in Milan last week saw players having to retrieve a towel from a rack in the corner of the court in a bid to limit its use.
The 21-year-old is a rarity on the men's Tour where it now seems the majority of players towel down after virtually every point, sometimes after a rally lasting one shot.
"And if he did, I knew there was a good chance I would play him in the group or the first match, especially if Rafa didn't play. It's been a very enjoyable few days so far, not just for me but also my team". Djokovic is looking to equal Federer with his sixth title at the O2, while the Swiss has another big target in view, his 100th career title.
As odd as it may sound, but Roger Federer actually must thank Novak Djokovic for him making it to his 16th ATP Finals. "It's probably one of the most prestigious events that we have, and just playing there is already an honour itself". "I'm going into the season finale (in London) with a lot of confidence and feeling good about my game".