Antonio Rudiger cannot be trust to play alongside Mats Hummels in Germany's backline, according to Patrick Vieira.
The Chelsea centre-half is partnering the Borussia Dortmund man for Joachim Low's side at the Euros.
Hummels recently returned from retirement but his lack of pace remains a concern.
The 32-year-old was consistently caught in behind during Germany's loss to France.
Rudiger is being played to counteract that deficiency but Vieira feels as if his decision making remains a flaw.
He said: "You need two around him to give him (Hummels) more protection but I don’t know if Rudiger is the type of player that you can count on him, he’s not the smartest one.
"Sometimes he makes a poor decision that gives his teammates a big big problems. We saw the goals that Germany concede against France he can do silly things the bite on Pogba he’s somebody that can lose his head in any moment during a game.
"I think Hummels is not the quickest one but he’s really smart and uses his brain to try to defend well but it’s going to be tough at this level for him."
Gary Neville echoed that sentiment and feels as if Rudiger can get pulled from pillar to post by his opponents.
He said: "Rudiger needs a project during a game, you need to give him an instruction you can’t leave it open to chance with him.
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"I think if you said to him go and stick to Cristiano I think he’s actually confident enough in a stupid way sometimes to think I’ll mark him out of a game and make sure he absolutely doesn’t get a kick.
"But I think if you say he goes there, you swap over, he does that I think you will end up confusing him and he ends up getting pulled up all over the place."
Despite such criticism Rudiger played in Germany's commanding 4-2 win over Portugal on Saturday.
Low's side conceded early on but responded with four unanswered goals to get their Euro 2020 hopes up and running.
The German boss hailed the performance of Robin Gosens, who scored his side's fourth.
"I don't know if it was the game of a lifetime for him, maybe he still has to play that," Low said.
"But an amazing performance from him. He worked very hard and on top of that he was a constant threat up front as well. That is exactly what we needed today."