Jurgen Klopp is known for his laid back and humourous demeanour, using intelligence as his preferred mode of attack.
But when the red mist takes over, there's little you can do to stop it - and even Klopp could not help losing his cool on Wednesday evening.
He was furious after Borussia Dortmund's goalkeeper Roman Weidenfaller was sent off in their opening Champions League encounter with Napoli.
In this perfectly timed photo, he appears ready to eat the official, or at least do him some serious damage!
Check it out below: