Manchester City were beaten 1-0 by Thomas Tuchel’s side on Saturday night in Porto as Kai Havertz’ first half strike proved to be the difference.
Guardiola named a starting line-up without a defensive-midfielder or a striker, while he also played with genuine wingers in a shake up of his normal system.
And German icon Matthaus is the latest in a number of ex-pros to reveal their disgruntlement at Guardiola’s tactics.
“With his line-up he stole the Champions League from the club and the fans and he has to rightly listen to the harsh criticism from all sides,” Matthaus said in his latest column for Sky Germany.
“I am sure that there will be internal discussions about whether to part with him. The players will doubt him since that final.
“He had to try something again, present an imaginary ingenuity at the worst possible moment and totally deserved to lose.
“How can you play without a defensive midfielder in the most important game in club history, who was on the pitch in almost every game of the season, who ensures the balance, who gives everyone involved the necessary security?
“Why did he leave Rodri and/or Fernandinho out, start six attacking players and also play without a centre-forward?”
City’s chairman Khaldoon Al-Mubarak appears to be fully behind Guardiola though, and vowed to splash the cash this summer to avoid a similar disappointment next season.
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Al-Mubarak explained: “One of the things I’ve learned over the years is, you need to constantly bring in talent into the team, refresh and particularly when you are at a high level and when you’re on the top.
“Having won the league, it is not the time to sit back and be content. That would be your biggest mistake.
“This is the time to send a strong message, that there’s no contentment, that you’re not satisfied with just winning the league.
“That’s great, but you want to win it again and you are committed and you are bringing more talent that is going to compete, not for the squad, but for the starting XI.
“We lose a very important legend in Sergio Aguero. They are very hard shoes to fill, but I’m confident that we will find the right player to fill those shoes.
“There are other areas within the group, within the team that obviously need investment. Not too many. It’s not about numbers, it’s about quality.
“I think the squad is a phenomenal squad. You don’t win the Premier League and you don’t reach the Champions League final if you don’t have an incredible squad – and we have that.
“We will bring quality into the squad in a couple of key positions.”