Benfica president Luis Filipe Vieira has informed those clubs chasing the signature of Alex Witsel that the midfielder will not leave for less than £31million.
The highly-rated Belgium international has a €40m release clause in his contract and that figure will have to be met if he is to move on this summer.
Witsel has been strongly linked with a number of Europe's top clubs, with the likes of Manchester United, Chelsea, Manchester City, Real Madrid and AC Milan all said to hold an interest.
It is easy to see why they are keen to acquire the 23-year-old, with his physical attributes and ball-playing ability likely to make him a star in any division across the continent.
Those looking to do a deal will have to dig deep, though, if they are to prise Witsel away from Portugal.
With the player having only arrived in Lisbon in the summer of 2011 on a five-year contract, Benfica know the power is in their hands and that they can hold out for the best fee possible.
"Every club knows what his release clause is," Vieira told Antena 1.
"If they come here and pay that fee, then there is nothing that we can do.
"We are very happy with Witsel and we do not think about selling him."