Sunderland will have to wait until next month at the earliest before they can sign Marcus Alonso, with West Ham United also interested in the left-back.
The Hammers have had a written bid for the Spaniard turned down, but Fiorentina want to see the 23-year-old in pre-season before deciding his future.
Alonso spent the second half of last season on loan at the Stadium of Light and performed well in what is traditionally a problem position for them.
However, having apparently missed out on midfielder Ever Banega, the Black Cats now have competition for Alonso.
Gustavo Poyet, though, has an extra bargaining chip in Modibo Diakite.
The French central defender struggled to adapt to English football last season but was a regular in Serie A after moving to Florence on loan in January.
Diakite started nine league games and two Coppa Italia games, playing at right back and in central defence as part of a pairing and a trio.
Until joining Sunderland, Diakite had spent his whole career in Italy, coming through the ranks at Serie B Pescara before moving to Lazio. With the Wearsiders, who yesterday revealed a new all-blue change strip, keen to get Diakite off their wage bill, he is sure to be offered in part-exchange.
Alonso played for Sam Allardyce at Bolton Wanderers and West Ham’s manager has already suggested a season-long loan with an option to buy at the end of it - but Fiorentina have rejected the idea.
Nevertheless, with captain Manuel Pasqual and Juan Manuel Vargas as competition, it is likely they will be prepared to let Alonso go later in the summer.
Banega, meanwhile, is expected to join Marseilles from Valencia for £8m. The presence of compatriot Marcelo Bielsa in the Marseilles’ dugout appears to have persuaded the 25-year-old to join them over the Black Cats.
Uruguayan coach Poyet signed three Argentinians – Ignacio Scocco, Santiago Vergini and Oscar Ustari – during the January transfer window.
Meanwhile, youth coach Chris Blake has left Carlisle United to take an analyst’s role with Sunderland’s under-21s.
He said: “I wasn’t looking to leave Carlisle but when Sunderland called and offered me the position I was very flattered.”