After making only one substitute appearance last season, it was hoped that the 29 year old would be back in action for United’s summer tour. But the rest of the squad set off for Chicago on Monday and Hargreaves will be left behind.
Sir Alex Ferguson told MUTV: "The bad news is that Owen Hargreaves is back in America seeing a specialist.
"He will not be ready for the start of the season. I do not know when he will be back."