MANCHESTER United star Brandon Williams appears to inhale nitrous oxide from a balloon near the club’s training ground.
The £60,000-a-week full back, 22, was a passenger in a parked Brabus supercar.
He was seen with a balloon in his mouth as he passed a friend a canister of the legal high.
A witness told UK Times: “It was so obvious to anyone driving by what he was doing.
“Anyone who follows United or football seriously would have recognised him instantly. It’s irresponsible considering he’s a public figure.
“He’s meant to be a role model for youngsters and upcoming footballers.
“Taking that rubbish, especially so casually, could be hindering his ability on the pitch.
“There is no doubt his manager will not be impressed by it.
“He expects his players to be completely devoted to their career, especially when they are attempting to break into the side.”
Nitrous oxide is an anaesthetic gas popular among young Brits who inhale it for a light-headed, short-lived euphoric high.
But taking the drug comes at the risk of heart attacks and brain damage, while prolonged use can lead to memory loss and vitamin deficiency.
It is a criminal offence to supply nitrous oxide to get high but not to possess it.
But earlier this week Home Secretary Suella Braverman pledged new measures to crack down on the “unacceptable” use of the gas.
She said: “I am clear that the use and proliferation of nitrous oxide is unacceptable and we will be announcing new measures soon.”
Manchester-born Williams has played just five minutes of football this season under ten Hag.
The defender joined his hometown club in 2008, rising through the Red Devils’ youth teams to make 51 professional appearances.
He has been linked with a move to Middlesbrough in recent weeks after failing to break into United’s first team.
Man United and his agent were contacted for comment.