The 19-year-old, following a muted first half, harassed Benfica right-back Douglas after the break with some powerful bursts on the ball and forged the opener when his fizzing free kick was carried over the line by debutant Mile Svilar with 25 minutes left.
But Rashford’s evening didn’t carry on for much longer: the teenager pulled up, removed his shin pads, and limped off feeling his knee in a state of discomfort.
And Mourinho, speaking after the game, confirmed that the teenager had picked up a knock during the closing stages of the game.
Jose: "Marcus felt something in his knee."
— Simon Stone (@sistoney67) October 18, 2017
Why the 54-year-old didn’t bring Rashford off immediately is a mystery. Sending on Anthony Martial straight after would have been the perfect message to send to the hosts, who now had no option but to attack and leave gaps further back.
Either way, bringing off Rashford at that point makes perfect logistical sense: he played nine games over September, alongside starting both internationals for England earlier this month.
An affliction of some kind felt dangerously just around the corner, and supporters will just hope this was a precautionary measure above anything.