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The reigning champion was in scintillating form against a hapless Schalke, storming into a 3-0 lead by half-time thanks to goals from Serge Gnabry, Leon Goretzka and a Robert Lewandowski penalty.
It got even better for Bayern after the interval as Gnabry completed a hat-trick before Thomas Muller, Leroy Sane and 17-year-old Jamal Musiala completed Schalke's misery.
While Flick was pleased his side laid down an ominous marker for the 2020-2021 season, he still believes it should have scored more in the first half.
"We have had our first game but we need to take things slowly," he said. "We played brilliantly but should have scored two, three, maybe four more goals in the first half.
"But it was important to show that we are on the right track this season as well. I am very satisfied with the performance. This is now a benchmark for both Gnabry and Sane and the whole team."
Sane – making his debut following his July move from Manchester City – felt he slotted in seamlessly with his new team-mates and was pleased with their appetite for goals.
"It felt very good to be on the pitch with the boys," Sane said. "It was a very good day. I feel completely at ease and knew that it would work out well with the team. Everyone was hungry. Everyone just wanted to attack and give full throttle."
Sane started his professional career at Schalke before his move to the Premier League in 2016 and he admitted to feeling sympathetic towards his former side after such a crushing defeat.
"Of course, I was at Schalke for a long time," he added. "To get such a defeat at the start of the season and it goes so haywire is difficult. I'm of course a little sorry."
Schalke has now failed to win in its past 17 Bundesliga games, with head coach David Wagner left to rue his side's "naive" approach against the domestic and European champion.
"That was bad," Wagner said. "We didn't play well; Bayern was outstanding. We have to shake ourselves now, accept this bitter defeat and show the reaction against Werder Bremen that we expect of ourselves.
"It was naive that we wanted to continue going forward after the fourth or fifth goal."
