Chelsea hold key as Spurs target Alex

But if Spurs are to sign the PSV Eindhoven centre half, they will have to negotiate with their London rivals to clinch the £14 million transfer.

Real Madrid are also interested in signing Alex, who knocked Arsenal out of the Champions League this season with his goal at the Emirates. But Real have learned that because of the complex nature of his transfer from Brazilian club Santos to PSV, he cannot move without Chelsea's involvement.

PSV technical director Stan Valckx yesterday denied the club had received any substantial offers for Alex but said: "There are two parties involved in this. Chelsea and the player himself."

When pressed about Chelsea's involvement, Valckx said: "It is something between Chelsea and PSV."

Alex has claimed he was poised to go to Stamford Bridge last summer but the deal was blocked by Jose Mourinho. It is understood he would favour a move to Chelsea, who have confirmed they have first option to buy him, if Mourinho leaves.

Otherwise he would consider other offers and Tottenham hope they can entice him to London.

There are conflicting reports regarding the nature of Alex's ownership.

PSV say the player is rented from Chelsea,who paid the initial transfer fee, whereas Chelsea insist he is a PSV player and that they merely have an option to buy him.

Alex was signed on the recommendation of Piet de Visser, Chelsea owner Roman Abramovich's personal scout.