Barcelona will head into the game after a disappointing defeat to Real Betis in La Liga on Saturday with Juanmi scoring the only goal of the game for the visitors.
Xavi spoke after the match and felt his team had not deserved to lose but is aware they must do a lot better at the Allianz Arena.
“We have to stop these counters. It’s a goal that annoyed me, because we had spoken in the week, that we had to make a foul (in that situation),” he said.
“We have to be more tactical. They can’t catch you on a counter. We can’t allow a goal like the one we conceded. It’s our mistake.
“Losing is too much of a punishment. It’s a shame not to take even a point. A pity, because we played really well for 25 minutes. Like against Villarreal our goal arrived when we were suffering, today we let in the goal when we were playing better. That’s football.”
Xavi then turned his thoughts to Wednesday’s match against Bayern which Barca must win if they are to guarantee a place in the last 16.
“I have told the players that I am proud,” he said.
“Now you have to compete like animals to win in Munich. We have no choice but to go to win, then we will see.”
Meanwhile, Bayern warmed up for the visit of Barca with a thrilling 3-2 win against Borussia Dortmund in the Bundesliga. Two goals from Robert Lewandowski and a Kingsley Coman effort gave the visitors all three points.