Okay, I've weighed up factors for and against a Federer victory today:
Reasons for Federer:
1) Federer leads the head-to-head 18-16 and GS head-to-head 6-5. Of all the member of the so-called Big Four, Federer matches up best against Djokovic.
2) Grass is Federer's best surface and Djokovic's worst. Djokovic doesn't move as well on grass (ergo can't defend as well) and is prone to slipping on this surface. Grass is the least physical of all the surfaces and so the age discrepancy should be less of a factor here. The last and only time these two met on this surface, Federer won in four sets.
3) Federer should be fresher coming into the match as he has spent much less time on court.
4) Djokovic looked very beatable to me on Friday, and if he turns up in that form today, he has very little chance unless Federe bombs.
5) Crowd will almost certainly be pro-Federer -- this bothers Djokovic psychologically and has adversely affected his performances in the past.
6) Federer is serving well this tournament and the outcome of their matches has historically been determined by Federer's first serve percentage.
7) The head-to-head this year is 2-1 in Federer's favour. Djokovic only beat Federer on the slow hard courts of Indian Wells (Djokovic's favourite), and even then was taken to a third set tie-breaker.
8) Djokovic prone to mental lulls in the course of best-of-five matches these days; gives away breaks of serve quite cheaply now.
9) Djokovic has a poor GS final record in recent years and may feel too much pressure to break his duck against the guy with the best record on this surface a la Nadal at Roland Garros.
10) Edberg a better coach than Becker? Haven't been impressed with Becker's approach from what I've seen in interviews.
Reasons for Djokovic:
1) Even though he hasn't played that well this tournament, he has been clutch on the biggest points when it matters. He has found a way to win while playing badly.
2) Younger and fitter than Federer so will have the advantage if it goes to a fifth set. Federer has a relatively poor five-set record.
3) Has the best return on tour; can possibly neutralise Federer's biggest weapon these days. Against Tsonga in R4 he won match point with a return winner that was eerily reminiscent of "that shot" against Federer in USO 2011 semi-final. Federer hasn't really played a good returner yet.
4) Federer's first serve percentage often drops when he needs it the most. In Indian Wells this year he was serving like a boss all through the tournament until he got to the final and lost to Djokovic.
5) Federer is more erratic these days and could start shanking.
6) Djokovic has been serving well this tournament; Federer's return isn't that good these days.
7) Even when Federer races out to an early lead, Djokovic has the guile to wrest the match away from Federer a la USO 2011 SF. He will not just lie down for Federer once things don't go his way. Federer still bears mental scars from that match?
8) His ground game is good enough to expose a weakness of Federer's, which is his poor lateral movement. Djokovic can achieve this by directing the wall at both wings during the rally and making the old man run from side to side and wear him out.
9) Surely Djokovic can't lose another final? It's getting quite embarrassing now and I'm sure the proud Serb will do everything in his power to avoid this.
But overall I'm going for Federer in 4. I sympathise with Djokovic and all, and he hope that he breaks his duck in major finals eventually, but I just hope that it's not this final in which he does it. He's still relatively young and will be the one of the big favourites for the US Open regardless of what happens today.