We noticed this in our weekly NFL notes from FOX that the Broncos/Vikings game in Minnesota was going to be broadcasted by FOX and not CBS and we wondered why. Normally, if an AFC team is at an NFC team, it's a CBS game just as it would be a FOX game if an NFC team is at an AFC team. The short story is that the NFL "flexed" the game to FOX since it took the Lions/Saints to NBC Sunday night and FOX only had 2 1pm games. Needless to say, FOX will gladly take Tim Tebow and some ratings points!
Here's the full story from our friends at Pro Football Talk.