Porto president Pinto da Costa would not sell striker Hulk for less than his €100million release clause, but admits the club have not received a bid for their star player.
Former Porto boss Andre Villas-Boas, now in charge of Chelsea, has been rumoured to be weighing up a bid to bring the prolific marksman to Stamford Bridge.
Real Madrid are also thought to be monitoring the situation but Da Costa claims he would not even swap Hulk for their main man Cristiano Ronaldo.
"At the moment, I would not swap Hulk for Cristiano Ronaldo," he told Porto TV.
"But our club have not received an offer for him, I believe these rumours are only created by the papers.
"Porto value Hulk at €100million (£87million) and I believe it will be difficult for any club to pay that."
Much of Porto's squad are sought-after following last season's heroics, with the club sealing a League, Cup and Europa League treble under Villas-Boas.
Radamel Falcao and Alvaro Pereira are also interesting Europe's elite, but Da Costa insists it will take a 'mad' offer to tempt them into breaking up their squad.
He said: "Falcao and Alvaro Pereira are not heading for the exit door. Only a mad offer could change our decision, but I am confident (of keeping them)."