Interesting draw...
I believe Stan Wawrinka might have the easiest road as he doesn't play anyone particularly dangerous to him till the QF, and even there is undefeated vs. Nishikori or Raonic.
Andy Murray, OBE has a pretty tough road as befits his recent lower ranking. First up, Almagro, who is no slouch on clay, but does occasionally beat himself. If he gets past the Spaniard, it doesn't get easier.
Roger Federer might play a couple of players early that have given him trouble in the recent past in Simon and Robredo. Then if he gets by them, he has whomever comes out of the Murray section.
Novak Djokovic's section looks fairly brutal at first glance, but only Fognini or Dolgopolov, who play each other again, are real clay court dangers.
Rafael Nadal should reach the QF without too much trouble, when he would likely play either Dimitrov or Berdych. If he has trouble prior to that, it won't look good for him.
Anyway, I won't be surprised if Nole withdraws because of his wrist.
Tournament directors don't like announcing top player withdrawals too soon as it can hurt them at the gate.
Respectfully,
masterclass