Emre Can has told Borussia Dortmund teammate Jadon Sancho to "grow up" following his breach of lockdown rules to get a haircut.
The 20-year-old was one of two Dortmund players, along with Manuel Akanji, to be fined $10,000 by the German league (DFL) after inviting a hairdresser into their respective homes.
Both players were pictured getting the trim without wearing any protective equipment.
Sancho labelled the DFL's decision an "absolute joke" in a tweet aimed at the governing body, which was later removed.
But Can feels it was an unnecessary mistake for his teammate to make, and suggested the incident shows Sancho still has some maturing to do.
"Jadon needs a little guidance," Can told Sky in Germany. "He's a great boy, also off the pitch. It's true that I get along very well with him.
"He just has to be a little bit smarter about these things. Everyone needs a hairdresser. He needs to grow up. He can't afford to make mistakes like that in the future.
"We as a team are also responsible. We are not annoyed by him. We know that he has to be more disciplined in some things. But he knows that too."
A statement from the DFL on Friday said: “The DFL has fined Manuel Akanji and Jadon Sancho. The players from Borussia Dortmund had obviously violated general hygiene and infection protection standards at home hairdressing appointments and in particular the medical-organisational concept of the DFL task force.
“There is no question that professional footballers also have to have their hair cut. However, this currently has to be done in accordance with the medical-organisational concept.”
Dortmund have not taken action against either player, and both were present in their side's 1-0 win over Hertha Berlin on Saturday, in which Can grabbed the winner.
"I don't think he does this on purpose to create a scandal," Can added. "Maybe he doesn't realise it, maybe he trusts too many people in some things.
"He needs people to guide him. That's where the environment is very important."
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