Bayern moved seven points clear at the top of the table at the time after blasting their way past their closest title rivals in a rampant 5-1 victory at the Allianz Arena.
However, Dortmund have since managed to embark on a fabulous run of form, closing the gap between themselves and Bayern to just five points in midweek after the Bavarians suffered a shock 2-1 defeat against Mainz on Wednesday.
And reflecting back on their earlier encounter this season ahead of Saturday's Klassiker at Signal Iduna Park, Tuchel says Bayern's comprehensive victory over Dortmund actually had a positive effect on his charges.
"The reverse fixture showed that you can lose by a high margin because of small errors. But you can learn from that,” said BVB boss Tuchel.
"The 5-1 loss in Munich has made us into what we are now. And we are very happy with that.
"You could see our improvements in the games against Mainz and Augsburg following that loss in Munich."
Dortmund, who are in the mix for Bundesliga, DFB-Pokal and Europa League success this term, pounced on Bayern's defeat to Mainz by downing Darmstadt 2-0 on the same night.
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But while Tuchel knows his side can edge even closer to Bayern this weekend with a win, he believes a defeat would effectively end their title hopes.
Tuchel continued: "We have the confidence to say that we're able to win.
"But we also can read the table. Bayern can turn it around decisively - which is why [we] expect them to be at their best.
"In order to beat Bayern we need a top performance. If we win, the situation will be different."
Tuchel also reiterated his admiration for Bayern counterpart Pep Guardiola, who is hoping to land another Bundesliga crown before departing for Manchester City at the end of the season.
"I have already talked a lot about Pep, he has set new limits. He knows I value his work, he is probably the best [coach],” added Tuchel.
"We want to beat Bayern but there will be periods when we have to suffer. But if we're brave enough to play to our limit we can also make Bayern suffer."