Porto president Nuno Pinto da Costa admits they will be powerless from preventing Jackson Martinez leaving should a club meet his buyout clause. It emerged over the weekend in the Portuguese press that Martinez had agreed personal terms with Arsenal.

Da Costa said: "I saw in many newspapers that Jackson played his last game for Porto against Penafiel. Interestingly, the same thing happened a year ago and then he played another 20 or 30 games.

"He's a player we want to keep, but we cannot stop someone paying the €35 million clause.

"Jackson went on vacation and so when he returns we will try to renew his deal just like last year."