The agent of Modibo Diakite admits Sunderland are keen to sell the defender.
Ulisse Savini said last week that Sunderland are looking to recoup more of their investment.
"The Viola want to bring Diakitè back to Florence but Sunderland - who has made a major investment in Modibo - wants to recover what they invested," he said.
"It was an idea that we had put up (the potential swap deal), but I think Alonso has many requests from the Premier so I see it as a difficult task. Diakite and Alonso are two different tracks at the moment."
