The 21-year old Boca Juniors star is rated as one of the most gifted youngsters in South America and has been in emphatic form term, scoring 21 goals in all competitions for Argentine club.
Chelsea boss Jose Mourinho was keen to get the signature of the youngster before bringing Radamel Falcao to Stamford Bridge in summer, but the transfer move was never finalised despite big interest from the Blues.
It is widely speculated that Chelsea are ready to meet £6 million asking price for young striker and complete transfer move in winter.
Chelsea have had a problem scoring goals as of late with the Chelsea strikers not finding the back of the net regularly. Diego Costa only most recently scored his 3rd goal of the season as he converted a beautifully executed free kick from Willian which was against Norwich City.
Chelsea then went on to secure the victory over Norwich City although the Blues played in dominant fashion, the scoreline speaks otherwise with just one goal making the major difference in the game.
Calleri could be the player Chelsea needs to pose a real attacking threat as he possess great technical ability as well as pace.