Bayern won the Bundesliga this weekend with a 1-0 win away at Frankfurt and are in a commanding position in their last eight tie against the Serie A leaders.
Heynckes insists that while Antonio Conte's side are up against it, they have the ability to pull off an incredible turnaround.
“Juventus are a top team and they have shown that so far in the Champions League and in Serie A. They are going to try and make the impossible possible,” he told a press conference.
Bayern went ahead in the first leg thanks to a David Alaba strike which caught Gianluigi Buffon unaware after a minute of action.
The goal led to Roten legend Franz Beckenbauer to describe the Italian goalkeeper as a "pensioner" but Heynckes hailed Juve's long-standing shot-stopper.
He continued: “I regard Buffon as one of the best goalkeepers in the history of football. He is a legend for me, a fantastic man and an excellent goalkeeper.”
Heynckes also says he will approach this match in the same way he tackled the first leg as winning is the only thing on his mind.
He added: “I think everybody knows that Toni Kroos is seriously injured and of course he’s not here.
"For us, despite the first leg result, nothing has changed fundamentally. We’ll approach the game as we did last Tuesday, so we’re going to try and win here in Turin.”