Former Bayern Munich goalkeeper Oliver Kahn believes that Borussia Dortmund do not have the depth to compete effectively both in the Bundesliga and in the Champions League.
The defending German champions progressed to the last 16 of Europe's premier club competition as Group D winners, but are 12 points off the pace in the Bundesliga.
"BVB played out an impressive Champions League group stage, which has to do with the fact that the team focused heavily on the competition," wrote Kahn in his column for Bild.
"However, in the Bundesliga, Borussia were missing the necessary concentration. The difference in their performances in the Bundesliga and the Champions League shows that quality in depth is needed in order to play at a top level in both competitions."
Dortmund won the Bundesliga in 2011 and 2012.
