Niko Kovac was unimpressed with Bayern Munich's lack of energy despite the Bundesliga champions thumping Mainz 6-1.

Jean-Paul Boetius silenced the Allianz Arena on Saturday with the opening goal in the sixth minute.

New arrivals Philippe Coutinho and Ivan Perisic were handed their first starts and the Croatia international set up Benjamin Pavard for the equaliser half an hour after Mainz's opener.

David Alaba's stunner put Bayern in front, then Perisic scored a header before Kingsley Coman, Robert Lewandowski and substitute Alphonso Davies secured an ultimately emphatic victory.

Kovac, though, was criticial of Bayern's start despite collecting a first home win of the season after being held by Hertha Berlin in their opener.

"We were too lethargic until the first cooling break," Kovac told Bayern's official club website.

"We didn't find a reply to Mainz's aggression, we thought it would be easy. Then our passing was quicker, we lured our opponents into the centre and had good moves on the wings.

"David Alaba's goal before the break was crucial. It was over when we scored our fourth goal. We go into the two-week international break happy."

Alaba's brilliant free-kick proved a key moment in the game and the Austria international agreed with Kovac's assessment of the game.

"We struggled to get into the game in the first 20 minutes; we weren't aggressive enough, we weren't quick enough," Alaba added.

"We also made a few mistakes, it's difficult then. Mainz did a very good job. We got a grip after the first cooling break.

"I'm proud to be part of this team. Everyone hits the gas in training, you can see everyone loves football. And when we put it into practice as a unit at the weekend it's great of course."

The international break offers a chance for Mainz to regroup, with Sandro Schwarz's side bottom of the table having conceded 12 goals in three games, scoring only twice.

"There's no point lamenting and creating unrest, not for us, not for the club," said Mainz defender Alexander Hack. "We must keep going, we now have two weeks to question things and to work."