The Bavarians are currently one of the form sides in Europe, having racked up 22 goals during their last five games in all competitions. Marseille, by contrast, have now gone eight games without a victory.
However, after noting the way in which the Ligue 1 outfit outmuscled Inter in the last 16, Heynckes is very wary of the threat posed by Didier Deschamps' men.
"We play every three days so I spent the full day yesterday analysing OM's football," the German coach told reporters on Tuesday.
"They are a great team with a great coach that I know well. I have got positive feelings about OM.
"They play emotional football and will probably be 100 per cent motivated. We will try not to fall into their trap; Marseille are a difficult team, very physical.
"We expect a tough game in this stadium but we are confident. I am focused on this match and we have a lot of respect for this team."
It has been claimed that the free-scoring Bundesliga outfit will take the game to Marseille but Heynckes was giving nothing away when it came to talking tactics.
"We know that scoring away from home is crucial, but we did not score in Basel [in the last 16] so I am not too concerned about this."
Meanwhile, the game is of extra significance to Bayern's France international Franck Ribery, who spent two years with Marseille before moving to Munich, and Heynckes revealed that the winger has been looking forward to the game for weeks.
"Ribery wanted OM in the draw and we understand his feelings [about the game]," he admitted.
"He is having a sensational season and it would be great if he could win a European trophy in Munich."
Bayern's meeting with Marseille in the south of France gets underway at 20:45CET.
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