Mainz called out Bundesliga champions Bayern Munich when Jean-Paul Boetius scored their opener at the Allianz Arena in the sixth minute.
But the response they got from the giants was devastating as Bayern smashed in six goals, beginning with Benjamin Pavard’s equaliser. Then David Alaba scored a superb free-kick, before the break.
Ivan Perisic increased Bayern’s lead nine minutes into the second half. Kingsley Coman, Robert Lewandowski and Alphonso Davies all added to Mainz’s misery.
Mainz were thrashed 6-0 in the corresponding fixture last season.
All of Bayern’s five Bundesliga goals heading into Saturday’s contest had been scored by Lewandowski, but the champions’ back-up brigade came to the fore this time around.