Celtic manager Ronny Deila insists Virgil van Dijk does not want to leave the Scottish Premiership leaders in January.
Celtic boss Ronny Deila says keeping his best players will take priority over acquisitions in the transfer window.
The 28-year-old from Pisa enjoyed separate loan spells with Catania and Chievo during the 2013-14 season and returns to Italy permanently to swell the ranks of the recent Serie B runners-up.
A statement published on Empoli's official website revealed the club possess an option to extend Guarente's deal at the Stadio Carlo Castellani by another year should they survive in the top flight.
The former Atalanta and Hellas Verona player will be presented to the media at 1500 BST on Wednesday.