Both Bayern Munich and Barcelona have both suffered defeat. Barcelona defeat was due to a red card that made them to play with 10 men against Monaco. Barcelona is weak when it comes to using 10 men to play against their opponents because the young players will be filled with tension and lacks the experience of playing with a man down.
I will not be surprised if Barcelona wins this match despite that head-to-head, they are the favorite. The secrete of winning Bayern and prevent them from scoring any goal has been revealed by Leverkusen and Aston Villa but I don't think that Barcelona will concentrate more on their defense because they're also a club that love dominating matches like Bayern. It will be strong match for both clubs.
Basically Barcelona and Bayern have almost the same strategy in playing on the field. These two teams both have the same attacking aggressiveness. So it is not surprising that when these two teams win the match, the number of goals they score is always large. And when these two teams meet in the 3rd UCL match, I don't think anything will change much about the strategy they will use. And I think this will really make the game very exciting. And making the Barcelona vs Bayern meeting one of the matches that everyone will be looking forward to currently in the UCL. And to be honest, I can't predict which team will be the favorite in the Barcelona vs Bayern match. And even though Barcelona is the host in this match, that doesn't mean Barcelona can be the favorite. Because we know that Bayern's mentality cannot be weakened even when playing against their opponents.