Jose Mourinho has demanded improvement from Henrikh Mkhitaryan and accused the Manchester United playmaker of "disappearing" during games.
Armenia international Mkhitaryan started the season in impressive form, supplying five assists in United's opening three Premier League matches before scoring in the 4-0 win over Everton in September.
Mourinho told reporters the former Borussia Dortmund favourite would return to face Brighton and Hove Albion at Old Trafford on Saturday but left him under no illusions that his standards have been noted as dipping sharply.
"I was not happy with his last performances," Mourinho said. "I'm not speaking about one or two, I'm speaking about three, four or five.
"He started the season very well and after that step by step he was disappearing. His performance levels in terms of goal scoring and assists, high pressing, recovering the ball high up the pitch, bringing the team with him as a No 10, were decreasing step by step.
"That was enough [to drop him] because the others worked to have a chance."
Such criticism of creative attacking players have become a theme of Mourinho's management over recent years.
Anthony Martial was urged not to "waste" his talent by his boss earlier this year, while Juan Mata – the Spain international who Mourinho sold to United while in charge of Chelsea – has been in and out of the starting line-up this season.
"I think they give what they can," the Portuguese said. "I cannot complain about the dedication or the motivation.
"They all try to give their best. I think we had an improvement with Martial. He's scoring more goals than last season.
"The other players are what they are. They have different kinds of qualities. Sometimes they produce a lot, and we have lots of chances and we don't score enough.
"The reality is that in the Premier League by not scoring enough we are still the second team with the [second] most goals scored."