Tottenham have suspended Yves Bissouma for their Premier League game at Leicester City on Monday after footage appeared to show the midfielder inhaling laughing gas.
Spurs have made the move despite the 27-year-old apologising for a "severe lack of judgement", having posted a video of himself on social media on Saturday which showed him inhaling from a balloon.
Possession of nitrous oxide - also known as laughing gas or NOS - for recreational use has been a criminal offence in the United Kingdom since 2023 and can result in a two-year prison sentence.
"We've suspended him from Monday's game," said Tottenham boss Ange Postecoglou.
"Beyond that, there's also some trust-building that needs to happen between Biss and me, as well as Biss and the group. That's what he needs to work hard at from now on - to try to win that back. He's going to have to earn that.
"The door is open for him and, hopefully, we can help him realise the decisions he makes impacts more than just him.
"Hopefully, it allows him to make better decisions moving forward."
Bissouma, who joined Tottenham from Brighton for £30m in 2022, played for 45 minutes in Spurs' friendly defeat against Bayern Munich on Saturday afternoon, before posting the video.
"I've been in the game for a long time and every time a situation like this arises, I've tried to look at them in a couple of different ways," said Postecoglou.
"One is, there's a person involved and, in this case, it's Biss and he's made a really poor decision.
"There are still sanctions involved, and some of those include education.
"The second part of that is he's a footballer and he has responsibilities. He has a responsibility to the club, team-mates, our supporters and everyone associated with the club and he's failed in those duties, so there's got to be sanctions for that."
Postecoglou further explained his disappointment at Bissouma's behaviour.
"There's the personal ramifications, because it's illegal," said the former Celtic manager.
"Then there's the professional responsibility - the example you set as a professional footballer - because there are so many people who follow the Premier League and we're all in a pretty privileged position.
"He's made a poor choice. But within that context, we all make mistakes, there should always be an opportunity there for rehabilitation and redemption for every human being, including footballers.
"That's up to Biss now."
BBC