The reigning champions face Atletico Madrid in their first Group A game.
Bayern had a reduced off-season as a result of their European success, with just 26 days separating their win over Paris St-Germain in the final and their opening Bundesliga fixture this term.
“It’s about playing one game at a time,” said Flick.
Bayern also won the Bundesliga and German Cup to compete a memorable treble last season, but several big names have since departed the Allianz Arena – among them Thiago Alcantara, who joined Liverpool, and Philippe Coutinho, who returned to Barcelona after a loan spell.
But Bayern boosted their ranks with four signings just before the transfer window closed, including bringing Brazil winger Douglas Costa back to Munich on loan from Juventus
“It is a different team from last season and each team has its strengths and weaknesses,” said Flick, who will be without the injured Tanguy Nianzou and Leroy Sane.
“For now, I am quite satisfied. We have only had one training week with everyone together, but now there is more solidity in our staff. What will be very important is to have no injuries.”
Atletico will be hoping to avoid a second successive defeat to German opposition after losing to RB Leipzig in last season’s quarter-finals.
Their summer signing Luis Suarez has scored three goals in three appearances since leaving Barcelona.
The Uruguayan will be partnered up front by Joao Felix, with Diego Costa ruled out with a thigh injury.