The 34-year-old ended Djokovic’s 23-match winning streak on Tuesday with a classy straight-sets victory in the group stage of the ATP World Tour Finals but knows he will need to be at least as good to repeat that feat in the final.
Federer dispatched fellow Swiss Stanislas Wawrinka 7-5 6-3 to keep alive his hopes of a seventh title at the year-ender, while Djokovic outplayed Rafael Nadal 6-3 6-3.
It sets up the perfect climax to the season between two players with 27 grand slam titles between them.
But Federer says Tuesday’s victory over world number one Djokovic will have no bearing on Sunday’s showdown.
“For me it’s an advantage because I guess it gives me a bit of confidence,” Federer, who has accounted for half of Djokovic’s meagre six defeats this year, told reporters.
“For him it’s an advantage because he gets a second chance, and he’s in another final. He’s played some great tennis since we’ve played.
“So, yeah, I still believe his confidence is slightly higher than mine with the amount of success he’s had this year.”
Djokovic, who won three of the year’s grand slams and has a career-best 81-6 record this season, is looking to crown an incredible year with an 11th title and fourth in succession at the O2 Arena.
Nadal described him as “almost unbeatable” on Saturday but the Serb still trails Federer 22-21 overall and says the Swiss plays a game he finds uncomfortable, especially over three sets rather than in grand slam play when Djokovic has the edge.
“I’ve lost against Roger three times this year. When he’s on, it’s hard to play him,” said the world number one.
“I think he also likes playing me because he has a variety in his game with the slice, he comes to the net, he takes away the time from me. We always play matches with a lot of tension.
“There is a lot at stake. I know I have to be on top in order to win against him.”
Federer was supposed to play Djokovic in last year’s final but pulled out with a back injury sustained while beating Wawrinka in a tempestuous three-setter.
That match ended with Wawrinka and Federer’s wife Mirka embroiled in a row after she called him a “cry baby” on court.
This time there was no drama as Federer hit back from 2-4 down in the first set to claim a quick victory.
(Reporting by Martyn Herman, Editing by Ian Chadband and Ken Ferris)