The striker had appeared to confirm that he would be joining West Ham a week ago, but Barca are reportedly looking at the Argentine.
West Ham United may have just spent £20 million on Andre Ayew, but it appears as though a seemingly-inevitable deal for another forward could be hijacked as Spanish outlet Mundo Deportivo report that Barcelona are looking to sign Jonathan Calleri.
Calleri, a 22-year-old striker who has starred for both Boca Juniors in his native Argentina and Brazilian side Sao Paulo, has been heavily linked with a move to the Olympic Stadium.
Last week, the striker appeared to confirm that he would be joining the Hammers when he was quoted by a Brazilian TV channel as saying that the deal was done, although he is still thought to be waiting for a work permit to clear.
However, according to Mundo Deportivo, that delay has allowed Barcelona to develop a further interest in the man who is currently starring for his country's under-23 squad at the Olympic Games in Rio de Janeiro.
The Spanish outlet claim that Calleri is one name on a limited shortlist of candidates being considered by the Catalan club as competition and back-up for the fearsome strikeforce of Lionel Messi, Neymar, and Luis Suarez.
The report alleges that Barca have revealed that they a targeting a non-Brazilian striker playing in Brazil, and strongly suggests that Calleri is likely to be that man.
The player himself seemed certain that he would be a West Ham player before too long, but with no further movement on the deal having been announced, Barca's interest could be a spanner in the works.
Even if Calleri was set on a move to London, it may well be hard to ignore any advances from one of the most prestigious clubs in the world, particularly as it would present him with the opportunity to team up with Argentine idols Messi and Javier Mascherano.