Rash was having a 26th birthday bash with friends and family.

But all the Red Devils were told they had to be in for training on Monday, as their planned day off was cancelled.

Boss Ten Hag revealed: “Yes, I am aware of it. I spoke with him about it.

“It’s unacceptable. I told him, he apologised and that is it. For us, it’s an internal matter.”

Dutchman Ten Hag refused to reveal if he had fined the £300,000-a-week star.

The manager put Rashford on the bench for Wednesday’s Carabao Cup fourth-round clash with Newcastle — which holders United also lost 3-0.

Rashford — whose actual birthday was the day before — was sent on in the 65th minute but had no impact as his poor season continues.

After hitting a career-best figure of 30 goals last season, he has only ONE in this campaign.

United have lost eight of their first 15 games in all competitions so far — their worst run since 1962.

Ten Hag insisted the striker was not left out of the starting line-up against the Toon as a disciplinary measure but as part of squad rotation to give him a rest.

And he believes Rashford is trying his hardest to turn things around.

The Dutch boss added: “He’s fitting in, he’s very motivated to put things right.

“I know how much effort he is putting in. He’s totally with us. I see him every day in training.

“So he makes one mistake but also off the pitch, what he is doing, how he lives.

“I’m sure he is doing everything right to help the team, to perform and to let us win.”

Rashford was pictured on the bench again on Friday.

This time, it was on the platform at Stockport station as he waited with his team-mates for a train to London ahead of the clash with Fulham.