Paul Pogba left Old Trafford on crutches after injury blighted his first start as Manchester United captain in the Champions League.
The midfielder was replaced after 19 minutes by Marouane Fellaini during United’s 3-0 win over Basel in the group stage.
Pogba failed to last 20 minutes of the Group A encounter at Old Trafford after stretching awkwardly to win the ball in midfield.
The France international immediately held his hamstring and signalled to the bench for assistance after only being able to take a few steps.
The 24-year-old limped off the pitch as Mourinho turned to Fellaini, who missed the weekend’s 2-2 draw at Stoke City, to fill the void in midfield.
And he was forced to leave the stadium on crutches as United await medical reports that will determine the severity of the injury.