The German champions raced to a 4-1 lead over Barcelona after the first 31 minutes and never looked back, doubling it after halftime and winning astoundingly against one of their European rivals.
Bayern Munich are now waiting for the winners between Manchester City and Lyon in the semi-final of the competition.
Flick is not getting carried away despite a big win in Lisbon and has encouraged his men to rest and focus on their next game as the main target is to hoist the Champions League trophy for the first time since 2013.
"I think we can enjoy an excellent game from our team," the German coach told reporters.
"Of course we are delighted with the way in which we have achieved this 8:2.”
"But we all know - and you could feel it in the cabin - that we still have a lot to do. We know how fast that can happen in football. It is important to look ahead to the next game.
"Our goal was to get to the semi-finals. We did that impressively. We are all very happy about that. But we also know that it is still a tough job to be where we want to be in the end."
“The way it was is impressive," he added. "And we have set a small fragrance brand. But even our experienced players know that it's about performing the same in the next game. We are preparing for this.
"The team put a lot of pressure on in the first half, forcing their opponents to make mistakes, and then the game of switching over the ball was just great. These are the things we wanted to do. And the team did a great job on the pitch."
