Failed medical cost Boateng Sporting move

"Boateng was here in Lisbon. He underwent medical tests and failed because of a knee problem. He had an operation on his knee at the age of 16 and he has been having problems for the last two or three years," Augusto Inacio told SIC Noticias.

Inacio's comments come after Sporting released a statement on Wednesday saying they had pulled out of the deal following a disagreement about the 28-year-old Boateng's image rights.

However, Sporting coach Jorge Jesus indicated on Thursday that a failed medical was the real reason for the deal falling through.

"The quality of the player is not in question," he said, adding that the club's medical staff "judged that other factors were important".

Boateng had appeared set to sign a two-year contract at the Estadio Jose Alvalade.

The former Hertha Berlin, Borussia Dortmund, Portsmouth and AC Milan forward was suspended indefinitely by Schalke 04 in May after the Gelsenkirchen club's Bundesliga defeat to Cologne.