By FOX Sports Staff
Jerome Boateng settled the match with an 86th minute header in a frenetic game that saw plenty of goalmouth action.
Thomas Muller had earlier levelled for the Bavarians shortly before the end of the first half, cancelling out Mathis Bolly's 16th-minute strike at the Allianz Arena. Andreas Lambertz then scored a second for the visitors in the 71st minute but Franck Ribery ensured that the lead stood for only two minutes.
The deciding goal did eventually come late as Bayern stood their ground and adapted to the aggressive tactics employed by the players from Dusseldorf.
Heynckes did not wish to comment on Fortuna's high-handed approach to securinga result and chose to focus instead on his players' self-belief. He also took it as an opportunity to remind them of the importance of approaching each game as it came and not let the hype of their domestic success get to them.
Bayern have lost just once in 25 league games while Fortuna are languishing in 15th place and therefore were not expected to provide as much of a test as they did on the night.
"Today's [Saturday's] game showed that we have not won games even before the kick-off," Heynckes told reporters in the post-match press conference.
"The team twice came back from behind and showed great morale.
"As long as we are not mathematically German champions, we will not accept congratulations."
Bayern next play host to Arsenal for the Champions League last-16 second leg and hold a 3-1 lead from the first leg.