I was at the game and it looked like Sanchez dislocated his shoulder. The bruising may be symptomatic of the internal dislocation...if the MRI showed a partial tear then he could be out for a while. Bruising of the Shoulder would not be the full extent of the diagnosis. Day to day may mean week to week. I doubt he starts Game 1. He could be back for game 3 or 4 if its a separated shoulder. If its a partial tear within the shoulder, you'd have to see if he can play through the "looseness" that occurs in the joint.
Either way, Geno will probably be the week 1 starter. Expect to see him get 1 qtr's worth of work against the Eagles on Thursday.