Manchester United defender Chris Smalling is pleased to have "brilliant" Henrikh Mkhitaryan back to his best form in a United shirt.

Mkhitaryan, 28, was bought from Borussia Dortmund for around €42 million last summer, but had struggled early to find space in Jose Mourinho's starting XI.

However, the Armenia international has become an influential piece at Old Trafford of late, scoring a crucial away goal in the club's Europe League round-of-16 first-leg tie at Rostov last week.

And Smalling hailed the former Shakhtar Donetsk's current form, telling the United Review ahead of Thursday's second leg: "Yeah, we are glad Miki [Mkhitaryan] is back, it is great.

"He had missed a few games but he came back and had an instant impact like he had never been away.

"It is great to have such great attacking options and Miki has been brilliant for us, because he is a threat that is very hard to defend against.

Henrikh Mkhitaryan celebrates his first-leg goal against Rostov. Getty

"As a player, he is very unpredictable. Every player in the world knows who Henrikh Mkhitaryan is. But it is one thing to know him and another to deal with him. I am lucky that he is on our team and I am not playing against him.

"He is often thinking one step ahead [in training], whether it is a pass or a dribble. He is deceptively quick as well and he is probably quicker with the ball than he is without, which is rare for a lot of players.

"He is a great, great asset for us."