Six defeats from their opening nine fixtures have left any Dortmund hopes of challenging for the title dead in the water, and their season is perhaps now just a case of hoping to challenge for UEFA Champions League qualification.
Jurgen Klopp's men have lost five of their last six Bundesliga games and are languishing in 15th place coming into Saturday's clash at the Allianz Arena.
Though suffering in the Bundesliga, Dortmund have won three from three in the Champions League, cruised through their DFB-Pokal second-round clash against St Pauli in midweek and overcame Bayern 2-0 in August's DFL-Supercup.
And former captain Kehl believes the bigger occasion can inspire Dortmund to snap their current domestic funk.
"Against Bayern we have often looked good," he is quoted as saying by Kicker.
"This is again possible if we play in a compact - then we have a chance.
"We need a bit of luck, but above all we have the will to do what is necessary in the league."
Tensions between Bayern and Dortmund are often fraught at the best of times, but this season has seen a war of words at boardroom level over a potential move for Marco Reus to Bavaria.
Bayern CEO Karl-Heinz Rummenigge has been vocal of his club's interest in bringing the Germany attacker to the Allianz Arena in recent months - a path trodden by Mario Gotze and Robert Lewandowski over the last 12 months or so.
A string of ankle injuries have hampered Reus this season, but his mental state will be under close scrutiny as he looks to sink a team he is ever-increasingly expected to join at the end of the campaign.
Reus' recent return has further boosted Klopp's options with the likes of Ilkay Gundogan, Henrikh Mkhitaryan and Shinji Kagawa also making comebacks from fitness issues.
Bayern coach Pep Guardiola was delighted to see Franck Ribery make his first start of the season in Wednesday's 3-1 Pokal win at Hamburg - the Frenchman scoring Bayern's third of the game via a Johan Djourou deflection.
"I am really pleased with his performance," Guardiola beamed. "We must not forget he was injured for such a long time, but he played really well."
Having played a full 90 minutes at the Imtech Arena, it remains to be seen whether Ribery will start again, but Guardiola's other star winger, Arjen Robben, is fit again after sitting out the Pokal clash with a trapped nerve in his thigh.
Guardiola does have concerns in the goalkeeping department though, with first-choice Manuel Neuer the only fit senior shot-stopper at the club currently.
Former Mainz keeper Heinz Muller has been training with the club recently and could be drafted in if Neuer suffers a late injury.