That's according to former Red Devils midfielder turned pundit Owen Hargreaves.
United's record signing limped off early into their Champions League group stage clash with Basel.
It looked like a hamstring injury and could keep the Frenchman out for a long time.
And Hargreaves, who has had a few injuries in his time, knows how damaging that could be for Jose Mourinho and his side.
On BT Sport he said: "He’s something special, hopefully he can just run this one off.
“It looks like he’s struggling. It was a bit of an awkward movement, just stretching.
“He clutched that hamstring straight away.
"He’s just over-stretched it.
“If you think about the quality United have in every position, this is the one player who they haven’t really got a replacement for.
“He’s a special player already, he will be the heartbeat of that Manchester United midfielder for a very long time."
