Jarrell Quansah hit out at Bayer Leverkusen's display after they were thrashed 4-1 by Stuttgart on Saturday.
Leverkusen's first Bundesliga game back after the winter break did not go according to plan, as Kasper Hjulmand's team were hammered at home.
Jamie Leweling, Deniz Undav and Maximilian Mittelstadt netted in a superb first-half performance from Stuttgart, who took a 4-0 lead into the interval.
It was the first time Stuttgart have had such a large leading margin by half-time in a Bundesliga match since September 1982, when they were 4-0 up against Nuremberg.
Alejandro Garnacho pulled one back for Leverkusen midway through the second half, but they never looked capable of mounting a comeback.
"We were miles off it," said Quansah.
"You wait so long to play the first game in 2026 and you show up like that – it’s not at the level. Especially off the ball. It’s all good having the ball, trying to play, but it’s what you do off the ball. We have to show a lot more fight.
"It should have been that we were fired up again. It shouldn’t take conceding any goal. That fire should have been in us from the start. Especially in front of our own fans – we can only apologise to them, to be honest.
"Everybody saw the performance, we didn’t show any fight. When you don’t show fight, that’s where it goes wrong."
Leverkusen have a chance to quickly get back to form when they take on Hamburg on Tuesday.
"We need to go into every game with fight, a bit of grit, determination – win our duels off the ball," Quansah added.
"We know we can play great football, we’ve done it against the best teams. But the best teams show what it means to get three points and to win, so we have to take this feeling now and use it as fire."