The Belgian picked up a niggle whilst on international duty with Belgium but recovered in time to take part in the 2-1 win over Greece.
But he was unavailable for the 2-2 drawn with Stoke City on Saturday – a clash, as Mourinho noted afterwards, that he could have influenced – with a calf problem.
And Mourinho, speaking at a press conference ahead of his side’s Champions League opener with FC Basel, noted that the 29-year-old was still unable to train with the squad.
“He had a [calf] problem with his national team and then he played a match against Greece,” he added, “and after the match he felt the problem. If his condition improves he will be selected, because I need him.”
Rival supporters often ridicule Mourinho for using Fellaini as an option off the bench in spite of the millions he has splashed out on other talents, but the Portuguese doesn’t care in the slightest.
Whether you like him or not, Fellaini changes the complexion of any game through virtue of his very presence. His cameo against Leicester City, for example, stopped the visitors right in their tracks. He is a bustling, awkward, bold influence that Mourinho clearly counts on as an alternative dynamic going forward, and supporters will hope to see him make a quick return to action ahead of a busy September schedule.