The Premier League champions are in Thailand as part of a visit to the Far East ahead of the new season and the club confirmed on Thursday that the England international had returned to the UK due to a hamstring injury.

But Rooney, while admitting to being disappointed, revealed that the injury is not as bad as first feared.

"Gutted to have picked up a niggling injury especially as training was going well," Rooney commented on his official Facebook page.

"Heading back to Manchester to have it assessed fully but early indications are nothing to worry about."

Initially, it was feared the forward would be out of action for around a month, but United manager David Moyes revealed on Friday that Rooney will be unavailable for "two to three weeks", meaning he should be ready for the beginning of the 2013-14 campaign.

The 27-year-old's future at Old Trafford was recently clarified after a prolonged period of uncertainty, which followed outgoing manager Alex Ferguson's revelation that the striker had handed in a transfer request.

However, new incumbent Moyes used his first press conference as United boss to confirm that Rooney would be staying at the club.