Federer has been really good when using that short, slice backhand to draw opponents closer to the net to open up points/rallies. I thought he used that technique really well during last year's French Open.
I think that Federer is going to play aggressively versus Nadal if they play on clay, to let the chips fall where they may. He can't just sit back and consistently outslug Nadal from the baseline. Against Nadal on clay especially, his backhand tends to cost him, while he is not able to generate enough great forehands to take control of the match.
i dont really recall him doing that as much as using the drop shot. but even if he does do that, this tactic DOES NOT WORK WITH NADAL.
the backhand chip short is a slow ball, nadal has plenty of time to get to his forehand, even go inside out or in (obviously to federer's backhand), and just pull up on the ball with that insane topsin he has, and feds stuck fighting off an insanly high ball to his backhand, which is a really difficult shot.
imo, for fed to beat nadal on clay in the FO, he needs to play like he did in madrid. the break points HAVE GOT TO BE CONVERTED. thats really the difference in all of their matches. in the Wimby 08 Final, Federer had 12 BP opportunites, and capitalized on only 1.
like i said, three things need to happen for Fed to beat nadal on clay.
1) Federer needs to be there mentally 100%
2) Federer needs to look to be agressive, use the dropshot , and come into net like he did in madrid at the right time.
3) Break point conversion needs to be 65-100%. I would even say 75%.