These guys haven't played real competitive tennis for a long time so of course it's possible. Expect rust, which means fitness and consistency issues. So, short rallies, good, long rallies, bad.
Advantage: Attacking dudes with heavy weaponry who can win points quickly.
Disadvantage: Baseliners (and to a lesser extent counter punchers) who normally win those 9+ shot rallies.
And Rafa is more at risk of an early upset than Novak because he's a "confidence player", i.e. he needs a streak of wins to be fully confident.