Former Bayern Munich midfielder Stefan Effenberg has advised Borussia Dortmund to change their attacking style if they want to succeed in the Champions League.
The German champions have been pitted against Manchester City, Real Madrid and Ajax in Group D.
"They will not achieve their goals with their offensive gameplan," Effenberg is quoted as saying by Kicker.
"Perhaps [coach] Jurgen Klopp should change their style a bit. You simply cannot keep up that attacking style of play in such a tough group.
"The important thing is to have a plan B for occasions like this. You cannot hit the gas like they do every three or four days over the course of the season."
Dortmund will begin their Champions League campaign with a home game against Ajax on Tuesday.
