Furious Schalke coach Andre Breitenreiter blasted his players' performance in training on Tuesday and told them it was "like a circus," local newspaper Der Westen reported.
After a run that has seen them take only four points from their last five league matches, the Royal Blues host runaway leaders Bayern Munich at the Veltins Arena on Saturday.
Last season, Schalke twice held Bayern to 1-1 Bundesliga draws, but Breitenreiter reportedly shouted angrily at his players because he felt their preparations this week were not going well enough.
Der Westen said the coach was angry when players did badly at one training exercise, saying: "What's wrong? That's like a circus. Zero quality, that's absolutely nothing."
With 10 players away on international duty, Breitenreiter had only had 12 players available for Tuesday's training session, with captain Benedikt Howedes back after suffering a hand fracture.
"I got along just fine. I don't have any fear of falling on the hand," Howedes said.
"Bayern are a huge challenge, but we've always been strong when we had the support of our fans. What's nice about football is that you never know the result beforehand."