Sunderland and Inter Milan are heading to FIFA over the future of Ricky Alvarez.
Tuttosport says Inter are insisting Sunderland stick to the original agreement, which was they'd pay €11 million to sign Alvarez outright if they avoided relegation last season.
However, Sunderland insist the deal is unacceptable given Alvarez's injury problems last term.
Inter have refused to budge and now have tabled all documents regarding the transfer to FIFA.
Sunderland are also expected to put together a defence, with the matter now heading to a tribunal.