Heynckes won the league four times as a player with Gladbach and later went on to coach them.
He says his contact with the club remains strong but that will not prevent him from going all out to take all the points on Friday.
"I still have a very good, friendly contact with them, but we want to win tomorrow's [Friday's] game all the same," he said. "We want a positive end to the year."
Clashes between Bayern and Gladbach were as big as Barcelona against Real Madrid when the two clubs were leading the way in German football during the 1970s.
However, Heynckes says the importance of the game has dropped in recent years with Gladbach spending time in the second division and only nearing their former glories last season under Lucien Favre.
"For me it is (a classic), but otherwise it is a game like any other," said Heynckes.
"It was a classic in the past, but now Gladbach are no longer on a level with us."
Seventeen points separate the two clubs in the table while Bayern enjoy an 11-point advantage over closest rivals Bayer Leverkusen.
"It would be a surprise for all of us if Bayern don't win the league this year," said Favre.
"They have strengthened their squad intelligently with the likes of Dante and Javi Martinez, who is the ideal alternative to (Bastian) Schweinsteiger and (Toni) Kroos in the midfield."
Fortunately for Favre, Martinez may not play on Friday due to knock he picked up in training while Arjen Robben is also likely to miss out for the Bavarians.
Nevertheless, Favre is aware that it "will be a huge challenge for us" to repeat their double victory feat of last season.
Favre also has a few injury problems to contend with, although Patrick Herrmann and Filip Daems could come through, while Alvaro Dominquez is suspended.