Manchester United midfielder Henrikh Mkhitaryan has responded to a public challenge from Jose Mourinho by insisting that he will fight to achieve his dream at Old Trafford. The 27-year-old moved to the Premier League this summer in a £26m ($32.3m) deal amid much fanfare after a stellar final campaign for Borussia Dortmund in which he scored 23 goals and registered an astonishing 32 assists, yet he has thus far struggled badly to establish himself in English football.

After initially being hampered by a thigh injury suffered on international duty with Armenia that was later aggravated on his first and only start for United against Manchester City, Mkhitaryan was not even handed a place on the bench by Mourinho for six consecutive matches after returning to first-team training. Such a curious 54-day absence was finally ended during last week's Europa League Group A tie against Fenerbahce, when he replaced Marcus Rashford with 30 minutes left to play as the visitors unsuccessfully tried to overturn a 2-0 deficit.

Mourinho pulled no punches in his assessment of Mkhitaryan's sluggish start following that insipid defeat in Istanbul, insisting that the former Shakhtar Donetsk playmaker had to improve in order to show that he deserved a place in the squad ahead of his attacking colleagues.

"He has to do more," he said. "It's as simple as that. We have big expectations at this club, lots of players for these positions and he has to play better than [Juan] Mata, [Jesse] Lingard, [Anthony] Martial – he has to play better than them.

"It's as simple as that. Every manager wants to win matches, every manager in the world wants to play the players that he thinks can help the team more, and I'm no different."

Mkhitaryan was once again omitted entirely from the matchday 18 for Sunday's (6 November) comfortable win over struggling Swansea City, but has resolved to continue to battle for his place.

"It is true that I get little time on the field, but I am not going to give in," the newly-appointed Unicef goodwill ambassador was quoted as saying by The Guardian. "I went a long way to play in Manchester United, so nothing will prevent me from achieving my dream. I will not retreat, I will find the strength to reach my goal."

Mkhitaryan is currently in Armenia, where he will captain Artur Petrosyan's rock-bottom side in Friday's 2018 World Cup qualifying clash against Group E leaders Montenegro at Republican Stadium in Yerevan. He will then hope to force his way back into the United setup after the international break as the Red Devils, currently sitting sixth in the top-flight, face a run of four home games in 12 days against Arsenal, Feyenoord and two meetings with West Ham United.