A hard course, but still featuring the best players in the world.
One would have to assume that the highest round will be played on Th or Fri, so you can discount two rounds for the most part.
A course with easy . flat greens, and a good chance for rain, will make for plenty of one putts. I.E......plenty of saves.
The only real trouble here, is the rough, and like I said......these guys are the best at the game. These guys will not be "slashing about", so at worst, the rough will cost a guy a shot on a hole. Eliminate the par threes, and add the few holes with decent birdie opportunities, and I say 85 will be a stretch.
I recommend the under, and strongly, at that.