Marcus Rashford was not included in Manchester United’s squad for the game at Fulham.
The England striker was forced to apologise to United boss Erik ten Hag after attending a nightclub party following last weekend’s embarrassing derby defeat to Manchester City.
But Rashford was missing at Craven Cottage due to injury after taking a “heavy knock” in training.
Reports emerged the day after the City match that the England international, who turned 26 on Tuesday, had gone to the Chinawhite nightclub for a pre-arranged birthday party hours after the Old Trafford loss.
“Yes, I am aware of it,” manager Ten Hag said of Rashford’s post-derby night out.
“I spoke with him about it. It’s unacceptable, I told him, he apologised and that’s it. For the rest it’s an internal matter.
“He’s very motivated to put things right. So, he makes a mistake, but that doesn’t say he’s not fitting in. I see him every day in training, what he’s doing, I know.”
Following the team announcement at Craven Cottage, Ten Hag told MUTV: “(Rashford) is OK, but not OK to start. He is not fit enough to start but it is about players who are available.
“(Alejandro) Garnacho can do the job very well, we have seen that often so I am confident.”