Nadal, if He makes that far.
If nadal had a severe injury like del Po had, it will take at least 4-5 months competing hard for him gain his old form, if already shows up playing perfectly, and make a run at AO, He was up to something that we don't know.
So I'd rather have Nadal that won't get to latter stages of the match and have Murray going against Djokovic (good match up for Murray) and have Fed deal with Ferrer.
In equal conditions Murray is a better opponent for Federer.
2X VCore Tour F with 6g at 12 o'clock ---Yonex PC Light. Stan is the MAN.