Ange Postecoglou has said Tottenham have suspended Yves Bissouma for Monday's Premier League opener against Leicester City after the midfielder posted footage on social media of himself inhaling laughing gas.
The Mali international apologised after clips emerged on Snapchat showing him using the Class C drug -- also known as nitrous oxide -- and Spurs released a statement stating it would be "dealt with as an internal matter."
Speaking at a Thursday news conference, Postecoglou suggested Bissouma had failed in his responsibilities as a role model and had to rebuild trust in his teammates as he sits out the club's first game of the season.
"I've been in the game a long time, and every time situations like this arise, and they do happen, I've always tried to look at them in a couple of different ways," Postecoglou said.
"One is there's a person involved: in this case it's Biss [Bissouma], and he's made a really poor decision. You want to understand that and want to try to help him through that and as a club what we can do to make sure he doesn't make those kind of choices and decisions in the future.
"With that context, there's still sanctions involved, and some of those sanctions are education and giving him a clear understanding of how wrong it was. You always want to give people an opportunity to learn from their mistakes.
"The second part of that is he is a footballer for this club. He has responsibilities. He has responsibilities to the club, he has responsibilities to his teammates, he has responsibilities to supporters and everyone associated with the club, and he's failed in those duties. There's got to be sanctions for that.
"He won't be available for Monday. We've suspended him from Monday's game. Beyond that, there's some trust building that has to happen between Biss and me and Biss and the group.
"That's what he needs to work hard at from now on, to win that back. That's got nothing to do with one game. He may be suspended for one game, but he has to earn that.
"The door is open for him, and hopefully we can help him to realise that the decisions he makes impact more than just him and allow him to make better decisions moving forward."
Nitrous oxide was made a Class C drug under the UK government's Misuse of Drugs Act last November. Possession of nitrous oxide, not used for pain relief purposes, is now an offence punishable by up to two years in prison, but it is unclear at this stage whether Bissouma will face any criminal charge.
Asked how Bissouma goes about rebuilding that trust, Postecoglou replied: "Behaviour, mate. It's quite simple. It's him making better choices moving forward and behaviour. He's obviously disappointed, and he was very apologetic, not just to me but to the club and to everyone involved.
"But that's just the first part of the process, the next part is behaviour now. Making sure that he does the things he needs to do, like for all of us. We all make mistakes. It is how you find your way back from those mistakes, and what you do is far more important than what you say."
Postecoglou expects £65 million ($83.2m) signing Dominic Solanke to be available against Leicester, while Richarlison has recovered from a calf problem but needs "match minutes over the next few weeks."