The United midfielder hailed his new team-mate after Matic helped Jose Mourinho’s men get off to a flying start with a 4-0 thrashing of West Ham on Sunday.
While two-goal hero Romelu Lukaku rightly got the plaudits, Matic was the midfield catalyst for most of United’s play.
Matic wanted to quit Stamford Bridge this summer despite playing a key role in their title win last term and missed Chelsea’s pre-season tour as he looked for a move.
But it was still a coup for United boss Mourinho to convince his former club to sell the Serbia international for £40m.
And it could be a deal that comes back to haunt Chelsea if Matic repeats Sunday’s performance on a regular basis.
Asked if he is surprised Chelsea sold him, Mkhitaryan said: “I am, but at the same time I am very happy that we have got him.
“Matic does a big job on the pitch. He tries to recover all the balls. He defensively does a big job.”
Mkhitaryan also hailed Mourinho’s other two summer recruits in Lukaku and Victor Lindelof, despite the Swede being dropped for Sunday’s win after struggling in last week’s Super Cup defeat by Real Madrid.
“It was not only Matic,” he said. “I want to mention as well the other two new signings, Lindelof and Lukaku.
“They are very good players. They are, I think, Manchester United players.
“Lukaku scored his goals and Lindelof is still going to have time to show himself. So I want to say all the players are good signings and they are going to help us a lot.”
Armenia star Mkhitaryan believes United are on the up again after winning the Europe League and League Cup last season.
He added: “As a player and for a club, you are always going to have ups and downs.
“I think the last few years was a little bit down for the club but since last year, and this year, I hope it is going be up for the club.
“We are going to try to do our best to bring the club on the level it was at before. It is always hard but we will try and do our best.”
