Henrikh Mkhitaryan is not injured but still needs time to adapt to the demands of Manchester United, according to manager Jose Mourinho.
The former Borussia Dortmund star has not featured for United since he was hauled off at half-time of the 2-1 defeat to Manchester City at Old Trafford in September.
Mkhitaryan had been struggling with a thigh injury but was left out of the matchday squads against Fenerbahce, Chelsea and City in the EFL Cup despite Mourinho stating he had recovered from the problem, prompting further speculation about his future at the club and even a '#freemkhitaryan' campaign from fans on social media.
Speaking ahead of Saturday's Premier League match with Burnley, Mourinho insists that he has faith in the 27-year-old's quality but warned that he must build up his sharpness before returning to the team.
"Sometimes I confuse the meaning of 'fit' in the English language - sometimes fit means that you aren't injured," he said on Friday. "Mkhitaryan is not injured, he is training with the team at 100 per cent.
"Some players have the profile of adapting easily, but some other players need more time to feel the intensity.
"Some players need time to feel the competitiveness and the level of work without the ball. Mikhi needs time to become the top player we know he can be.
"Of course we believe in Mikhi and sooner or later there will be no problem."
United bounced back from their 4-0 thrashing by Chelsea with a 1-0 win over City in the EFL Cup last-16 on Wednesday, in which Michael Carrick produced a fine performance in the heart of midfield.
The veteran has played in each of United's last three wins in all competitions, and Mourinho could only express his admiration for his impact.
"One thing is to be 25 years old, another is 35. That's the logic of things. But the only thing I can say is that he's phenomenal, no doubts about it," he said.
"I think I have to manage him, I cannot expect from Michael what I can from [Marcus] Rashford or [Ander] Herrera in terms of playing seven consecutive matches. But he's phenomenal.
"There is no relation to victories but, for sure, he gives us important things - stability in our game, mental freedom to the other guys around him to be more offensive. He's not just a player, he's someone who has a big understanding of the game.
"You cannot stop the clock. It's a pity to have some players who become older. In five years' time, [Lionel] Messi will be 34 and we'll all be crying.
"Michael is such an important player and he's very difficult to replace."