Valencia president Juan Soler claims they are trying to sign Manchester United winger Cristiano Ronaldo.
Ronaldo has been at Old Trafford for three years
Spanish reports quoted Soler as saying: "I have always said it will be difficult. But nothing is impossible.
"Until they tell us no several times we will not give up. At the moment it's a priority and we have until 31 August."
The Portugal international, 21, has been linked with a move to Real Madrid, however Manchester United have stressed the player is going nowhere.
But Soler, who has already signed Fernando Morientes and Asier Del Horno from the Premiership, added: "First we will negotiate with the English club and then the player."
Ronaldo's future has been in doubt this summer after he was quoted as saying he wanted a move to Spain after his World Cup spat with Wayne Rooney.
But United boss Sir Alex Ferguson insists the winger is going nowhere.
Last week Ferguson said: "Without any question, Ronaldo will be our player next season and for the rest of his contract.
"I haven't paid much attention to what Cristiano is supposed to have said about his future.
"I haven't spoken to him since the World Cup."
Ronaldo, who joined Manchester United from Sporting Lisbon for £12.24m in August 2003, is under contract until 2010.