But the 28-year-old returned to action for Armenia this week in World Cup qualifiers against Montenegro and Kazakhstan, scoring in the latter.
And Mkhitaryan has revealed that he is now fully recovered from the small knock that kept him out of United's last Premier League fixture.
Henrikh Mkhitaryan has said he is fit for Manchester United's match against West Brom
Mkhitaryan scored in Armenia's 2-0 win over Kazakhstan on Sunday
"I just had a minor injury and couldn’t play against Middlesbrough," Mkhitaryan said.
"Even though I was on the bench. Thank God, everything is fine now, I feel well.
"I had a slight injury, I talked with the coach and together we decided, I'd better not play against Middlesbrough not to risk my health.
Man United's selection crisis ahead of West Brom clash
Wed, March 29, 2017
Manchester United could be facing a possible selection crisis ahead of their clash with West Brom this weekend
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Jose Mourinho could be facing a selection headache this weekend
"When there is a risk of injury, it is better not play one match than risk missing a longer period."
Jose Mourinho would have also been pleased to see both Marcos Rojo and Antonio Valencia come through unscathed in their respective internationals.
The United boss has some defensive injury concerns going into this weekend after both Chris Smalling and Phil Jones withdrew from the England squad.