Manchester United manager Erik ten Hag says it was "unacceptable" of Marcus Rashford to go a nightclub party after last weekend's embarrassing derby defeat to Manchester City.

The homegrown talent has managed just one goal for the misfiring Red Devils during a poor start to the season on both an individual and collective level.

Rashford has looked a far cry from the player that plundered 30 goals for United last term and his off-field decision-making came into question after last Sunday's 3-0 defeat to City.

Reports emerged the following day 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.

Asked about Rashford's post-derby night out, Ten Hag said: "Yes, I am aware of it.

"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."

Ten Hag repeated it was an "internal matter" when asked if Rashford had been fined for an incident that he says will not impact his availability for Saturday's crunch Premier League trip to Fulham.

The United boss also clarified that his place among the substitutes in Wednesday's 3-0 Carabao Cup exit to Newcastle was due to rotation rather than punishment.

Rashford was dropped to the bench at Wolves last season for timekeeping, but Ten Hag rejected the notion that the academy graduate is not attuned to his demands.

The United boss said: "Your suggestion is not right. He's fitting in, he's very motivated to put things right.

"I know which effort he is putting in. He's totally with us.

"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.

"So, he makes one mistake but also, off the pitch, what he is doing, how he lives, and I'm sure he is doing everything right to help the team to perform and to let us win."