German champions Bayern eased to a five-goal demolition in Tuesday's fixture in Munich after Besiktas were reduced to 10 men early in the match.
Any hope of a competitive result at the Allianz Arena were dashed when Domagoj Vida saw red for a mistimed challenge in the 16th minute, as braces from Thomas Muller and Robert Lewandowski and a Kingsley Coman goal all but secured Bayern's passage through to the quarter-finals.
However, head coach Heynckes refused to get too carried away post-match as Bayern made it 14 successive wins across all competitions.
"It's very difficult for any team to play in the Champions League with 10 men," Heynckes said post-match. "I still believe Besiktas are a very good team, with many experienced players that have played across Europe.
"I'm very happy that we won so comfortably against such a team.
"We will still prepare as normal for the return leg. You cannot take any risks in the UEFA Champions League."
"I think we saw two different halves," he continued. "In the first half there wasn't any tempo to our game, our passing was off and it allowed Besiktas to attack us more.
"The opener before the break gave us a psychological advantage and in the second half we saw a different Bayern team. We scored some great goals and played some good football. Of course, I'm satisfied with the performance."
The only blight on Bayern's victory was the early withdrawal of star attacker James Rodriguez.
James was replaced by Arjen Robben just before half-time and Heynckes told reporters: "He felt his calves stiffen up. He will be checked over tomorrow [Wednesday]."