Ole Gunnar Solskjaer has denied claims that Mason Greenwood has been dropped as punishment for poor time-keeping.
The teenager has missed the last two games against Newcastle and Paris Saint-Germain but there has been mystery as to why.
Solskjaer said after the 4-1 win at St James’ Park that the England forward was not fit enough, before claiming he had a "niggle" ahead of the meeting with PSG.
Subsequent reports had claimed that Greenwood, who has been in training all week, was being punished for being late to training, something which the Norwegian has denied ahead of United’s clash against Chelsea in the Premier League.
"He made a mistake with England this summer and suddenly all the English press go after him, and that’s something we have to go after," the United boss told reporters.
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"He’s a fantastic boy to work with and I have to disappoint you, he's never, ever late for training and he’s never a problem when he’s at the training ground.
"I’ve seen the stories and some ex-United players talking about him but they don't really know what they're talking about. We have photographers outside the training ground every day and they can see he’s on time every day.
"I don’t know where these stories have come from. He's got a good family behind him, a good background in the academy and he's a good trainer, he trains really well.
"I cannot believe all these stories about him not being professional, that's something we have to deal with with many players. Many other players at United have had that."
Greenwood could be back in contention to face Chelsea along with Harry Maguire and Edinson Cavani, who both missed the trip to Paris.
On Cavani, who could be in line for his debut, Solskjaer added: "Edinson wants to tick all the boxes that he's gone through in his programme and be ready to make an impact. His last preparation [session] was going to be today and I will have a discussion with him."
The fixture at Old Trafford on Saturday evening is the first home game since the dismal defeat to Tottenham before the international break and Solskjaer is hoping his side can right some of the wrongs of that performance.
"I don't think anything will erase that memory, it'll always be in the history books and we have always got to live with having that result and that performance," the United manager said.
"You can look back at that performance and see what the different reasons were behind the result, but we have got to focus on moving forward.
"It's happened so many times at this club that you have results that come out of the blue, or setbacks that you have to bounce back from and so far we have bounced back well from it. But now it’s about consistency."