Should he beat Djokovic tonight, Federer can seal a seventh career season-ending title, and his third in a row.
The 31-year-old's career had appeared to be on wane until this season’s grass-court campaign got underway. A barren spell of Majors stretched from his Australian Open win at the start of 2010 until Wimbledon 2012, as fitness troubles and the seemingly uncheckable rise of Djokovic took their toll.
Obviously that did not tell the full story – Federer was still the king of the indoor game, retaining his ATP Finals titles throughout this fallow patch – but the return to form that saw him reclaim the world number one spot post Wimbledon was remarkable even by his standards.
One thing that has been maintained throughout is the 17-times Grand Slam champion’s popularity, a popularity that saw him garner the lion’s share of support in his semi-final, despite facing a British opponent in Andy Murray.
Federer feels his timeless, classic style of play may have something to do with that.
“I guess because I've been in the game for so long, many people just enjoy watching me play or feel like it's a throwback maybe to ‘back in the day’, the times when they used to play with one-handed backhands,” Federer mused after his straight-sets revenge win over Murray, who beat him in the Olympic final.
“I don't know what it is, but I do get a lot of support and do appreciate it. I don't remember the last time I didn't get any support.”
Much of that backing did come from a sizeable Swiss contingent, as is often the case in ‘international’ London, but Serbia’s Djokovic will not be short of backers. His fans may have been fewer in numbers, but they have been the noisiest so far, not least during his Group A win over Murray.
Federer has the edge in terms of the overall head-to-head and, after snapping a hoodoo that saw Djokovic win six out of seven around his remarkable 2011 ascent, the Swiss has won their last two matches.
An in-form Federer enjoys playing Djokovic, and the Swiss appears to have studied his game to the extent that nothing will surprise him. However, he is not considering his 16-12 record as any kind of indicator.
“I love playing against Novak. He's had a great year. He's had a great tournament so far,” Federer said.
“To me, the head-to-heads don't always tell the truth. I think with Novak we always have close matches, especially the last 10, 15 matches have been very back and forth. Similar with Andy (Murray), as well.
“I don't know what I like or don’t like about Novak's game. It's pretty straightforward. We both play aggressive tennis. We're natural attackers. That makes for exciting tennis.
“I think he's similar in a way to (Nikolay) Davydenko in his defensive skills. And he can turn defence into offence quickly too.
“I think his movement is obviously outstanding, especially on the hard courts. I just think he's good off both wings. He goes for it when it's important and he can deliver.
“Yeah he's obviously cleaned up his serving game. He's volleying cleanly. That gives him opportunities.
“Then when he's confident, he's a great frontrunner. He returns well. He has many assets to his game that makes him a very difficult competitor to play against.”
Djokovic, meanwhile, played his semi earlier on Sunday, so when he spoke to reporters his final opponent was still undecided.
In an exchange that has now become typical of the man, the ‘Djoker’ discussed his take on Serbian national identity, before dishing out chocolates as an end-of-season gift to journalists.
“I'm trying to take the best from my culture. In that way, I consider myself a Serbian, proud Serbian,” Djokovic said.
“Why not? I always try to use the opportunity to promote and present myself because of the past that my country had.
“Unfortunately we had a lot of bad times in last two or three decades with wars, economic crisis, politics and everything.
“So sport is one of the ways to give people hope in a way. It's a very positive message that athletes in general from Serbia are sending to the people.
“We get also a lot of appreciation and positive reaction from Serbian people. That's something that always inspires me and drives me to make more success in my tennis.
“Before we get to being Serbian, whatever happens tomorrow, I have a surprise.
“Thank you for your cooperation throughout the whole year. I have a little chocolate treat for everybody. If you would be kind and accept my present to you.”
Puns on the duo ‘serving up a treat’ notwithstanding, and discounting local disappointment at Murray’s exit, London could not have asked for more than a clash between the world number one and the dominant player on this surface.
History and recent form backs Federer. But Djokovic will always back himself in what promises to be an enthralling battle.
The ATP World Tour Finals starts after 7.45pm UK time on Monday night – follow live commentary from the O2.