Porto coach Vitor Pereira has refused to rule out the departure of midfielder Joao Moutinho.
New Tottenham Hotspur manager Andre Villas-Boas admitted on Wednesday that he would be interested in signing the 25-year-old Portugal international.
Although he admits that he wants the player to stay, Pereira understands that a move could happen this summer.
"I have not spoken with Villas-Boas, but it is natural that he likes Moutinho," he told reporters. "I like him, too.
"Clubs cannot just not sell. We really want him to stay, but this is football and there are release clauses.
"The only thing we can do is achieve results with what we have got."
Moutinho is believed to have a €40m (£31m) buy-out clause in his contract with the Portuguese champions.