Manchester United have confirmed striker Wayne Rooney will fly home from the club’s Far East tour after being ruled out for a month with a hamstring injury.

Rooney suffered the injury in training yesterday and scans have revealed the full extent of the damage.

“Following a scan this evening on a hamstring injury sustained in training, it has been decided Wayne Rooney should return home immediately for further assessment and rehabilitation,” the club said.

The news is an unexpected development given United only landed in Bangkok yesterday and went straight to their hotel for a short rest ahead of what turned out to be Rooney’s single training session.

Sixteen hours later he is on his way to the airport to begin the marathon journey back to Manchester.

If Rooney is ruled out for a month it would mean he could feature in the Community Shield against Wigan at Wembley on August 11.

However, given his obvious lack of match practice, it is difficult to see how he could be involved in the following week’s clash between England and Scotland, or the league opener at Swansea on August 17.

There was even a picture distributed of Rooney at today’s training session laughing with Patrice Evra that was distributed by United’s own photographer, although the pair were sitting on a step and the forward was not wearing boots.

And amazingly, the incident comes just a day after manager David Moyes revealed United staff had told him Rooney had returned for pre-season training in his best shape for years.

Rio Ferdinand expects there to be an extra sharpness about Manchester United during their pre-season campaign due to the desire to impress new manager David Moyes.

“It’s natural that everybody is trying to impress on this tour,” Ferdinand told www.manutd.com.

“When you get a new manager you want to show him that you should be in the starting XI for that first day of the new season. That process has started already.”