Moussa Diaby had reached an agreement with Sunderland to join the club this summer, but the move was cancelled due to administrative reasons. Diaby's time in the Saudi Pro League and his limited recent appearances for the French national team did not allow him to obtain the points required for the UK work permit (GBE). He needed a minimum of 15 points to play in England and did not meet the necessary criteria, which ended the possibility of him joining Sunderland.

A transfer of Moussa Diaby to AFC Sunderland failed due to a lack of playing eligibility.

Intermediaries contacted several English clubs, including Sunderland, Aston Villa, Tottenham, Crystal Palace, and West Ham, to assess a possible January deal for 26-year-old French international winger Moussa Diaby. Talks did not progress beyond the initial stages. According to sources, a potential move was not feasible due to the tax implications of a mid-season return to England, as players returning from Saudi Arabia face a significant tax penalty if they come back before being away for two years. After the financial impact was understood, Diaby's representatives began to consider clubs in continental Europe. TEAMtalk reports that negotiations with Inter Milan have reached a late stage for a deal structured as an initial loan with an obligation to buy in the summer for approximately €35 million. In the current Saudi Pro League season, Diaby has made 16 appearances, scoring 2 goals and providing 5 assists. Transfermarkt estimates his market value to be €28 million. His previous transfers include a €60 million move to Al Ittihad in July 2024 and a €55 million move to Aston Villa in July 2023.