Lukaku, who opened his account against Real Madrid on Tuesday, added two more goals to his Man United tally with a smart finish in the first half and a beautifully guided header just after half time.
And Matic duly dictated proceedings in the middle, shifting the ball around at will alongside Paul Pogba and impressively breaking through the lines.
Speaking after the game, the 54-year-old was full of praise for the way in which the pair have seamlessly transitioned into life at Old Trafford.
Jose: "The PL has taught me you have to adapt immediately. Matic-Lukaku have years of experience compared to Lindelof who needs time." #MUFC
— Shamoon Hafez (@ShamoonHafez) August 13, 2017
United were, it has to be said, up against a relatively poor, unprepared West Ham side, but the blueprint of his plan for this season was clear, and the aforementioned pair were at the heart of it.
Mourinho inherited a side that, in the eyes of his predecessor, was to be moulded into a disciplined, technically adept unit capable of keeping possession. This failed spectacularly.
What does work, however, is a powerful spine and a direct, bullish attitude going forward, and Mourinho has signed two players with vital Premier League experience capable of doing exactly that from minute one. He does not, after all, want to avoid falling into the same hole United failed to escape from last September.