But Dortmund has not lost a game in their home stadium. Bayern Munich couldn't beat them and they won their home games in the Champions League. Barcelona is playing strange because it is hard to come up with an explanation for their underperformance in La Liga in the last few games. They are the overwhelming favorites and have played so well against Real Madrid and Bayern Munich and then they lost so many points against supposedly weak opponents. I think it should be a good game, but it's hardly predictable. Both would be quite safe if they win the game as 15 points would presumably enough to win the ticket into the next round.
To beat Dortmund is not easy for them because Dortmund is currently at the top of the league standings, the point is that this match is very interesting, they will compete fiercely to be able to take tickets to the next round.