Matthaus branded Guardiola 'egocentric' for his insistance on changing tactics in big games.
This season, Guardiola changed formation to an unconventional 3-5-2 for the Champions League quarter final defeat to Lyon after a fine tactical performance to beat Real Madrid in the last-16 by playing 4-3-3.
Matthaus said in BILD: "With Pep Guardiola I have the feeling that he always wants to do something special in big games.
“Barcelona had a DNA, a system he pulled through. Pep was successful there. With Bayern and City, he tried it over and over again with changes and failed again and again.
“He always wanted to show that he could do even better. I would like to tell him: Pep, you are a giant trainer – but please keep your system!
"I would describe it as egocentric: Yes, that's a harsh word, but it is due to what he did: At Bayern, Robert Lewandowski even had to play left wing once. That did not work out at all."