Arsenal target William Carvalho will be out of action for at least three months after fracturing his tibia, his club have confirmed.
The Sporting Lisbon youngster suffered the injury during the Under 21 European Championship held in the Czech Republic.
The Portuguese club expressed their "indignation" at the news that the midfielder will miss the start of the new campaign.
"Sporting hereby express their indignation that William Carvalho has returned with a stress fracture of the tibia without this having been reported by the clinical staff of the National Under-21 team or any of its officers to the management of Sporting," Sporting wrote on the club's Facebook page.
"Only yesterday, Monday, on the return of William Carvalho to training the medical staff of Sporting identified an issue with the player and, curiously, only today at dawn the Portuguese Football Federation sent Sporting clinical newsletters referring to the seven Sporting players who participated in the Under-21 European Championship.
"The clinical report selection, referring to William Carvalho, says the player never had any physical problem.
"The player denies this and says that the clinical department was aware of the player's complaints.
"As a result, the player William Carvalho faces a spell out of between 10 to 12 weeks."