Heynckes, 72, came out of retirement this month to take caretaker charge of the Bavarians until the end of the season following the sacking of Carlo Ancelotti.
Bayern have since regained some form under the former Real Madrid manager and head into this week’s European Cup clash on the back of a 5-0 thrashing of SC Freiburg in the Bundesliga.
Speaking of Heynckes and ahead of the visit of Celtic to the Allianz Arena, Hummels said: “To be honest, I hadn’t been thinking about the Celtic game until now.
“But we are at home and we are the ones who want to be dominant.
“We’ll sit down and have a team meeting about Celtic and take it from there.
“But I don’t think we are under pressure. Last season, we lost at Atletico Madrid in our second game in the group, too.
“It was an ?important win for us on Saturday. Apart from a couple of chances we gave Freiburg, it was really a good performance from us. Now we want to build on this win.
“Jupp Heynckes is demanding in training. He wants us to play with great intensity and we showed that. He constantly monitors us and corrects us when we are doing something wrong.
“He had a conversation with all of us. I liked what he said to me.”