The Englishman begun life under Mourinho as a substitute but slowly asserted himself as an indispensable member of the Portuguese’s squad, making 53 appearances (more than any other Man United player) and claiming 11 goals in the process.
He has now claimed three major trophies, alongside making nine international appearances, ever since making his senior debut just 15 months ago.
And Meulensteen, speaking earlier this week, was full of praise for the way Mourinho has handled him at Old Trafford.
“I like Marcus and I’ve worked with him when he was a little kid coming in to the Cliff at seven years of age,” he said. “He came in with a smile and left with a smile.”
“He couldn’t wait to start training and training was always short for him. There was only one level of energy that he would bring.
“I bumped into him recently at Michael Carrick’s testimonial and we had a chat.
“He’s still got those things and that’s important because as a professional you get exposed to a lot and you need stability in your life.
“I’m so happy that he has already got so many games at United and he’s only going to get better the more that he plays and the more things that he gets exposed to.
“But a lot depends on what type of striker Mourinho brings in. If they spend a great deal of money on someone there might be a chance that Marcus is again shifted out to the left or right.
“He can play there for sure but his best position is up front. I really hope that any new signings don’t sideline Marcus completely because that would be a real shame.”
No matter what Rashford achieves in his career, from either World Cup glory or depressing loan move to West Bromwich Albion, supporters will point towards those swashbuckling opening few months under Louis van Gaal as the period that laid the foundations for his career.
But I would contend that, actually, these last nine months under the Portuguese will be the period Rashford looks back on as the most important. He was undoubtedly raw and exciting, but under Mourinho he developed the necessary footballing intelligence to thrive at this level on a constant basis.