Sporting Lisbon president Filipe Soares Franco has opened the door to selling midfield stars Joao Moutinho and Miguel Veloso.
Arsenal are eyeing Sporting captain Moutinho, while Manchester United are weighing up a bid for Veloso and Soares Franco said: "All Sporting players, in general, have buyout clauses. And these clauses are there as a basis to begin negotiations.
"It is obligatory."