Antonio Valencia’s early thunderbolt set Manchester United up for a 4-0 win over Everton, but they needed a flurry of late goals to finally take down the visitors.
Former Everton striker Romelu Lukaku set up Mkhitaryan to sidefoot United’s second after 83 minutes.
And Lukaku slammed in a third heading into stoppage time before Anthony Martial converted a late penalty.
And Mourinho, whose side have now won 4-0 three times in the Premier League this season, believes tonight’s victory was their best performance so far.
The Red Devils manager told Sky Sports: ”I think the performance was very good, especially in the first 30-35 minute.
“It was probably our best performance of the season.
“We pressed them and they did not have a chance to get out, they did not have a shot, it was very impressive.
“After that, Everton’s good players came out and showed their qualities.
“They gave us difficulty but I looked behind me on the bench and saw alternatives.”