For the second straight season, Barcelona are in danger of failing to make the knockout rounds of Europe's Premier club competition after accumulating just one win in their opening four group stage games.
Even a win against the Bavarians might not be enough for Barcelona if Inter Milan beat the group's whipping boys Viktoria Plzen.
Bayern Munich have already booked their place in the knockout stages and a win for Julian Nagelsmann's men will see them confirmed as group winners.
Kahn says Bayern will be highly motivated to claim all three points in Spain.
"We have nothing to give away in Barcelona. We want to achieve our goal and finish first in the group," Kahn told reporters on Tuesday.
"It is the strongest group, someone had to pay; Bayern, Inter or Barcelona. It's not over yet. We have the utmost respect for Barcelona.
"The performances they show in the league are strong, they're outstanding. It is always a very important match between two great teams in Europe."
Bayern beat Barcelona 2-0 in the corresponding fixture during the first round of matches.
