Three points separate the two heading into the game with Bayern top of the Bundesliga while Dortmund sit second - although that could all change come the final whistle.
"We have worked outstandingly on the training field and in meetings over the last 4½ weeks".
The Dortmund boss has acknowledge his side's subpar form, admitting they "need to do a few things differently" to improve but also stressed that "if we win this, we are back at the top of the table".
Dortmund were made to pay for their missed chances when Lewandowski flicked Joshua Kimmich's cross home, a deflection off Julian Weigl looping the ball over Burki.
The match lived up to its top Bundesliga billing with an entertaining first half and with Bayern gradually taking control.
Dortmund have now won just one of their last seven games in all competitions, a miserable run which leaves them also facing a group-stage exit from the Champions League, where they have just two points from four games. "It looks now he can play from the start against Dortmund".
The first half was a fast, open affair with plenty of chances.
"We turned in an outstanding display against a very good team today, especially in the first half", Heynckes told the Bayern Munich website.
Dortmund's Pierre-Emerick Aubameyang, the top scorer last season in Germany just ahead of Lewandowski, has now failed to score in each of his last five games, although he still has 10 for the season.
"There are going to be tough times, and right now is a tough time - but I believe in our team and I think we can bounce right back".