Roger's interview gives a lot of insight into why he thinks Rafa is so tough:
http://www.asapsports.com/tennis/2006mcarlo/042306RF.html
I expecially liked this comment:
Q. You obviously felt you had to attack. You made a lot of what are supposedly called "unforced errors." Did you feel you had to try and keep the pressure on him all the time?
ROGER FEDERER: Well, I mean, he leaves me no choice. I'm not going to start looping the ball if he's in the middle of the box, you know. He obviously plays a lot of shots, you know, that tease you to come in. It's obvious I'm going to make the unforced errors because I'm the guy who's pressing and not him.
So, you know, the unforced error stat, I don't care really, seriously. That's what I was really actually angry about at the French Open, people telling me I was going for too much.
They should play him and then see if they're not gonna go for it, you know.
This is interesting too:
Q. Would that be the start of the third set, when you broke him and then you looked pretty comfortable, and suddenly he breaks back.
ROGER FEDERER:
Yeah, I mean, obviously it happens and he plays very well every point of the game, you know. No matter if he's down Love-40 or 40-Love, you're always going to get the same guy, you know. That's the same with me, you know. That's what the lower-ranked players tend not to do, you know, is they go for too much when they're losing or also when they're winning. So it's obvious that you get broken sometimes.
But I just thought, you know, I was not maybe serving well enough or just playing well enough from the baseline to really, you know, win some games. I just thought I gave him a little bit too much there.