Tarvaris Jackson‘s knee bruise, suffered late in the first quarter of last night’s preseason win over the Ravens, is in fact something a little worse than a mere knee bruise. It is actually a sprained MCL – at least according to PFT’s league sources. Said sources indicate that Jackson will be kept out of the third preseason game, against Pittsburgh, but will return for the finale. This sort of buggers the Vikings‘ plans given that Brad Childress had said the starters would play into the third quarter against the Steelers. Now Gus Frerotte will get those reps with the first team. Presumably, this means Jackson will play more in the last preseason game than you would expect a starting QB to play – unless the coaches think he’s already gotten enough work, and would prefer to protect him instead.