Robin van Persie has warned Manchester United that Marcus Rashford may always have a weak spot in his back even after he's recovered from injury.
Rashford suffered a double stress fracture in his lower back during Manchester United's FA Cup third-round replay win over Wolves.
The striker is facing a spell of up to three months on the sidelines.
Former Holland international Van Persie sustained a similar injury during his own playing career, which kept him out of action for some time.
Van Persie did return to playing, and enjoyed a successful career at the top level, but he has warned Rashford that he himself never truly recovered from the injury.
"I had a similar injury, a stress fracture in my lower back," Van Persie told the Premier League.
"I was out with that for four months. You can't really do much, just rest and let it heal.
"But it is a difficult one because it always stays a little bit of a weakspot.
"Even now, it is not that I'm like in pain or something, but it's a sensitive area. So you have to be really careful with that."
United boss Ole Gunnar Solskjaer provided an update on Rashford's situation following the Red Devils' defeat by Liverpool on Sunday.
"Marcus suffered a stress fracture against Wolverhampton," Solskjaer said.
"I don't know how long he will be out for, we will give him enough time to heal. Normally six weeks before you get going slightly probably, and then he will need time to get match-fit again."
