Peter Fleming, the respected doubles champion of the early 80's claims that the main difference between Borg and nadal is that Borg had a more powerful 1st serve. Fleming feels that both guys are evenly matched elsewhere on the court. Fleming claims that Borg used to be crap on grass untill one year he was practicing his serve and something clicked and he had a huge 1st serve. If that is the case, then Nadal need only work on getting his 1st serve speed to say 130mph, which he can do on a more consistent basis. I think Nadal has to do more but there is no doubt if Nadal could serve as well as say Federer then he would have a chance at every major outside of clay with that sort of delivery. It would make his life easier. I remember last year Nadal made some modifications to his serve at Queen's last year and he later got injured and resorted to his old style. I personally feel that he has a decent serve already, he just needs to vary it more rather than hitting 90% of serves DTL with spin.