IMO, we should start with a double pivot & use Suarez as an impact super-sub.
Even if he's match fit, he still hasn't integrated into the team. So if he starts & ends up having no impact we're left with no tactical options apart from subbing him for Pedro/Munir. Whereas playing with Masch in a double pivot would be a sensible strategy in an away game against RM as it would mitigate the risk of counter-attacks, provide us with numerical superiority in midfield, and allows us to better contain Bale/Ronaldo; and we would still have Suarez as our trump card.