Anyone expecting Benfica to win against Chelsea is not being serious. If Mourinho wasn't appointed as Benfica manager of recent would they have expected Benfica to win against Chelsea at Stamford bridge? That aside, Chelsea have just lost to Bayern Munich which is a stronger team than them presently. But Chelsea are stronger than Benfica so they are to win Benfica with or without Jose Mourinho.
Why would you even say that? Did you just start watching football today? Or have you never seen a smaller team beat the bigger team? It's not like Chelsea is one very good team; they struggle with smaller teams in the league, too, so what makes you feel Chelsea can't lose to Benfica?
This is not even about Mourinho taking over Benfica; they've not been better under Mourinho. Benfica is not a small team, and we all know how the Champions League is. Teams don't come here to respect anybody; they're all looking for the win.
Chelsea is obviously the favorite, but Benfica has a chance to win that game.