The 19-year-old was suffering from growing pains at Old Trafford in Mourinho's first years in charge.

As a result, Rashford featured less regularly than in his breakout campaign under Louis van Gaal.

And the forward's form dipped in front of goal too for Manchester United.

However, much of this was down to the ongoing back strains he was suffering from.

According to The Sun, Rashford's condition got so bad he was unable to travel to games on the train at times.

United's away trip to Chelsea at the back end of last season saw him flown to London rather than with the squad.

And that was due to the fears of what damage sitting still on a train would do to the teenager.

Rashford has grown an inch, having stood at 5ft 11in when Mourinho arrived in the summer of 2016.

Manchester United forward Marcus Rashford is now free of his back problem

But now, The Sun add he is free of the problem and has fully recovered.

Mourinho was concerned any exposure of the ailment would see Rashford targeted by defenders.

Since pre-season, though, the England international has looked sharp.

And following a solid start against West Ham in United's 4-0 Premier League win on Sunday, Rashford is expected to start regularly this term.

United are next in action on Saturday when they travel to Swansea for a 12.45pm kick-off.