The question now becomes: can he make me believe he has a chance to beat Rafael Nadal in the finals?
For Federer to win this match, he must do three things in my opinion. Get off to a fast start, keep serving well, and get to net.
For Nadal to win, he must clean up his entire game, as it has been sloppy at times so far in Paris, and he must do what he always does against Federer: pound the backhand until it breaks down.
When you look at all the aspects of this match, this is by far Federer's best shot to beat Rafa in Paris.
Looking at shot by shot for both players, I see things stacking up like this.
The forehands are a tie. It comes down to Rafa's spin and depth against Roger's power and placement. Federer's has been better the past two weeks, but I will never doubt Nadal's forehand.
With the backhand I still give the edge to Nadal. He hits his forehand more, but when he wants to, he can rip his backhand. Federer has been pretty good with his one-hander so far in Paris, but it can start to leak at times, so the edge goes to Nadal here.
The serve—especially the way these two weeks have gone—definitely goes to Federer. Nadal has struggled with it so far in Paris, and after Federer's dominating service performance in the semis against Djokovic, Nadal better watch out.
When you look at overall momentum, it also goes to Federer. He is coming off his best match of the year against the hottest player the tour has seen in years.
Many had already penciled in the Nadal/Djokovic final, so you know the Fed express is feeling good about himself at this moment.
Having said all of that, there are two reasons I still give Nadal the slightest edge in this match.
The first reason is Nadal's intangibles on the clay. He is the greatest to ever play on the dirt, and he knows better than anyone what he must do, not only to help himself but how to put doubt in his opponent's mind, to win.
The second is the history these two have in Paris. In their previous four matches at the French Open, Nadal has won all of them. There must be a little sticking point of this in Federer's mind, and it obviously isn't a good one.
In the end, this is by far the best shot Federer will have at beating Nadal at the French Open, and I believe it will be a classic match between these two rivals and kings of the sport.
However, I see Nadal escaping with the win in a thrilling match: 6-3, 4-6, 7-5, 6-7, 6-4