By all accounts I've heard, Favre will be fine for Sunday. Remember, he'll have had a few days of extra rest.
Weather could end up posing a bigger problem for Oakland than Favre's health will for Green Bay.
Favre will probably come up about 50 yards short of the all-time yardage record. That'll have to fall in St Louis, unless Favre throws for his usual 5 picks and two dozen yards there.
Will JaMarcus Russel start?