Lol, Napoli is not as bad as you imagine because anyway, at this moment Napoli also seems to have improved performance for the better. Because after all, in Napoli's last two matches in Serie A also the fact that Napoli managed to win with a big score. Also, currently Napoli are also at the top of the standings in group C and besides, if you look at the available odds at least Napoli still have a chance to win. So yes, a draw and or win or lose can happen in this match, and even though Real Madrid is a very good quality team. But still, matches in the Champions League will never be easy because if it was easy, surely Real Madrid could beat Union Berlin with a big score in the previous match. But in reality, Real Madrid were only able to win 1-0 against Union Berlin and at least that shows the competition in the Champions League will never be easy.
But, both Lecce and Udinese are mediocre teams in Serie A, so even though Napoli win with big margins, it will be not same when they match against Real Madrid. Real Madrid is playing with a well organized strategy, while Napoli is playing with their physical appearance and individual skill. For me, I don't think playing with individual skill will able to beat a team play.