Henrikh Mkhitaryan is a doubt for the Manchester derby after the Armenian FA confirmed the midfielder has suffered a thigh injury which could take around 10 days to heal.

Mkhitaryan picked up the knock in an off-the-ball collision with Marek Suchy during the first half of Armenia's friendly with the Czech Republic on Wednesday and was taken off as a result.

Tests results on the 27-year-old's thigh injury were "not encouraging" and he now faces a race against time to be fit for one of United's biggest games of the season against Pep Guardiola's Manchester City at Old Trafford on September 10, live on Sky Sports 1.

The Armenian FA ruled Mkhitaryan out of their game against Denmark on Sunday.

A statement released by the Armenian FA read: "As reported, senior national team captain Henrikh Mkhitaryan received an injury against Czech Republic and as a result was unable to continue the match.

"Mkhitaryan has had a medical examination in a clinic in Mlada Boleslav. Unfortunately, the results are not encouraging.

"Mkhitaryan was found to have an injury in the lower third of the left thigh muscle. Such injuries usually require a week to 10 days to heal, which means that Mkhitaryan will miss the Denmark-Armenia match on September 4."

The former Borussia Dortmund playmaker returned to Manchester on Saturday to be assessed by United's medical staff at Carrington.

He tweeted: "My dear fans, I appreciate much that you worry about me, thank you! I'm now back in Manchester for treatment and hope to be fit very soon!"

Czech Republic captain Suchy, who was involved in the challenge that injured Mkhitaryan, was unapologetic when asked about the injury the United player sustained.

Suchy told Sky Sports: "I think it was not some really hard challenge, he was a fast player and I was just standing there.

"We hit each other and I hope he will be okay and it will not be so hard for him and he will not miss too many days. This is football and I will not think about it much more."

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