The Belgian midfielder is being targeted by several top European sides, with Arsenal, Chelsea, Real Madrid and Inter Milan all making overtures towards the 20-year-old.
However, Lille president Michel Seydoux has shocked them by slapping a £43 million price tag on the player.
According to reports in the Sun, Seydoux said: "The price is 50million euros - and we'd like to make that clear in advance.
"We are at a stage when the club is having discussions about what to do. It depends on the offers we get.
"Nobody is unsellable. We would be able to look for replacements with the money we would receive."
The player told L'Equipe recently: "I feel ready to make it to the next level at a big club.
"I stayed in Lille this season because there were still things I had to work on, things to prove. But now, I'm ready."
"Paris is not for now," he added. "Paris is magical, as they say. Of course it attracts me, but for now, no. In France I do not want to build a rival club to Lille.
"After France, I want to go abroad", he concluded.
The question is, which club will splash out £43million for him?