The Frenchman had to be taken off in the first half against Basel after appearing to injure himself stretching for the ball.
While he managed to walk off the pitch unaided, fans were shocked to see him using crutches following the match.
The short clip posted to Twitter shows Pogba in a United tracksuit making his way out of the ground.
He stops to chat to a security guard before leaving.
The £89m player has been in good form for the Red Devils this season and the sight did not go down well with fans.
“These next few weeks are going to be tough without Pogba,” one wrote.
Another added: “Please come back quickly.”
Mourinho has since revealed Pogba could be out for a “few weeks” after the hamstring injury, but said the squad can deal with his loss.
“Squads are for this, squads are for injuries, squads are for suspensions,” he said. “We don't cry with injuries.
“So if no Paul for Sunday, we have (Ander) Herrera, we have (Michael) Carrick, we have [Marouane] Fellaini and we have (Nemanja) Matic."
Fellaini replaced the ex-Juventus man and showed his worth, by scoring the opener in United’s 3-0 victory.
