A favourable draw could do a lot for Andy at the French open, if it opens up like it did at the AO or in fact like it did in 2011 when he got to the semis (I think he only met one seed which was Troicki in the 4th round) it is possible.
He's not favourite by any means and a true clay court specialist will trouble him of course, but if he gets to the semis then there is every chance, and if it is against the other 3 here is the H2H
Djokovic is 2-0 on clay
Nadal is 4-0 on clay
He has never met Federer on clay which would be the most intriguing of the 3 as arguably Fed is the better clay court player than Andy but with his recent form suggests it could be tight.
If there was a time to play Nadal then this year would be it, assuming of course he even gets to the semi and they could even meet in the quarters.
Ferrer would be difficult on clay but i would still give that match up 50-50 on clay, i think Andy's back was too problematic in 2012 for him to play at his uppermost best and still managed to take a set, which leaves Djokovic.
Djokovic is the real stumbling block of course but then that is the case on all surfaces, as it is clay i would lean towards Nole.
So my perfect draw for the RG would be for Andy to be in Fed's side with Fed vs Nadal in the quarters and playing 5 long sets where Nadal wins narrowly but taxes his knee sufficiently for it to become a burden in the semis with Andy
the final, well if Andy does get there we can only hope for either an inspired Andy or a shock exit for Nole in a previous round.