Atletico Madrid chief executive Miguel Angel Gil Marin admits they're attempting to land Porto striker Radamel Falcao.
Should Madrid secure Falcao's signature, it could set off a series of transfers around Europe, with Gil admitting the Colombian's arrival could trigger Diego Forlan's departure.
Gil told FCInter1908.it: "At the moment we are not interested in selling Forlan, since we have already lost Aguero, but we are currently trying to buy Falcao from Porto.
"If we were to close that deal, we would listen to offers for Forlan."