Luis Enrique went send Barcelona out to draw with Paris Saint-Germain on Tuesday but admitted he could change the system.
Barca lead 3-1 from the first leg and with three away goals are in a comfortable position, but Enrique insists the tie remains a dangerous one.
He stopped short, however, of saying he would settle for a draw to guarantee safe progression.
''The difficulty lies in the game overall. They're an opponent with a negative result who won't hold anything back,'' he said at a Press conference, AS reports.
''We're going out to win the game. We want the ball and we have to be prepared for a game similar to the first leg. We have to assess the game.
''[The first leg] was a very good result but not definitive. We need another big game. Talking about a percentage chance of going through would be misleading and poor preparation.
''I don't see us as favourites [to win the Champions League]. We're one of the candidates, as are the others. Of the eight left, four will go through. There's a lot of work left to do.
''I always want a positive result. The goal is to qualify but I understand victory is always the best result. There will be times we suffer, as happened in Paris.
''The goal is to qualify and I don't settle for results that aren't victories.
''We have a positive feeling about this game. We know them well because we've played three times against them this season. We should enjoy days like this.
''Change the system? Maybe. We might change it but it won't be because [Zlatan Ibrahimovic is playing] or anyone else.''