Rafa must be the biggest favourite before Nole and Roger. But he's vulnerable, Gulbis would've won him with some testicular fortitude. And if Nole gets to his peak level, he'll beat Rafa unless somebody has already beaten Rafa.
And it's hard to name anybody outside these. Wawrinka plays well, I think only the big names are unbeatable for him. Avoiding them in his quarter, he can make the SF. But to make the final, I think he needs somebody else to take out the big names. Ferrer of course is dangerous on clay, yet I see him a bit vulnerable. And Tsonga, Berdych, or maybe even DelPo or Murray, could make the SF with a good quarter. But I can see the final only with two players of Fedalovic.