The 35-year-old feels such defending on Tuesday men will see them exit the Champions League at the hands of Carlo Ancelotti's men
Bayern Munich striker Claudio Pizarro is worried about his side's defending of counter-attacks ahead of their clash against Real Madrid.
The Bundesliga champions suffered a 1-0 loss in Madrid in the first-leg of the Champions League semi-final, and host the Spanish giants on Tuesday.
Bayern prepared for the return leg with 5-2 win over Werder Bremen, but their defensive problems were highlighted as they twice had to come from behind in the game.
Both goals Bayern conceded were on the break, and Pizarro said the same mistakes would be just as costly against Real.
"We conceded two goals via counter-attacks in the first half. We can't afford to let that happen against Real, so we'll have to be on our toes," the Peruvian said.
"We played well in the second half and managed to score the goals to win the game. It was important that we won the match today and I hope we can do the same on Tuesday."
Bayern attacker Thomas Muller preferred to look ahead, with his team concentrated on the Champions League having sealed the Bundesliga title in March.