And he duly responded with his first goal since January and a tidy, notably fluid performance alongside Anthony Martial going forward.
Speaking after the game, Rooney expressed a desire to maintain his pressure on the first team over the next few weeks.
“You want to play football and I liked being back out there today,” he said.
“It was important for the team to win today and set up a big game on Thursday, but of course to score today – it’s always great to be on the scoresheet.
“I’ve had injuries and you want to play of course. Just as I am getting my getting chances coming off the bench I’ve picked up a few injuries which has been frustrating.
“Nothing big, but small injuries which have set me back in terms of choices for the team. I’ve come back, I feel strong and thankful to play today and to score.”
Ibrahimovic’s injury has suddenly thrust Rooney, following a lengthy spell of anonymity, right back into the limelight during what promises to be an explosive end to the season.
Mourinho will know that counting on Anthony Martial and Marcus Rashford alone could be treacherous; they are, after all, still in the nascent stages of their careers and largely inexperienced when it comes to dealing with closing out a season, and supporters will hope that Rooney – perhaps as his last gesture in a United shirt – can step up and deliver.