Buster Olney of ESPN is reporting that Miguel Cabrera has a small fracture under his right eye as a result of taking a hard grounder off his face in yesterday's game. It is described as a non-displaced fracture in the orbital floor. His vision is reportedly fine but he will miss a "couple of weeks". I imagine they will proceed cautiously with this type of injury though, so opening day may be in jeopardy.
It does not sound like he will miss a big chunk of the regular season if he misses any games at all. The worst part may be that he won't be able to get more repetitions at third base before the regular season. I'm sure he needs all the work he can get over there. I doubt he needs much time to get his bat ready. He could wake up in the middle of the winter and be ready to hit.