Sevilla president Jose Maria del Nido is adamant that Geoffrey Kondogbia is not for sale after completing the signing of Uruguay Under 20 international Sebastian Cristoforo.
Kondogbia only joined Sevilla from Lens last summer, but has already been linked with a move to a bigger club.
Premier League heavyweights Arsenal, Chelsea, Manchester City and Manchester United are all reported to have shown an interest in Kondogbia, along with Real Madrid.
However, after seeing the likes of Alvaro Negredo, Jesus Navas and Gary Medel all leave Sevilla during the transfer window, Del Nido does not want to lose Kondogbia.
"He is not for sale and this year whoever wants him will have to pay his buy-out clause of 20million euros (£17.2m)," Del Nido told a press conference to present the capture of Cristoforo.
Highly-rated midfielder Cristoforo has joined Sevilla from Penarol on a five-year contract and has cost in the region of €2.25m (£1.93m).
The 19-year-old will help to fill the void created by the sale of Medel, who followed Negredo and Navas to the Premier League by signing for Cardiff City on Saturday.
Cristoforo told Sevilla's official website: "I have arrived at a big club in Sevilla. This is a great opportunity for me, I am very happy and I can't wait to start.
"I didn't come to cover a position or to replace another player. Medel is a very important player. I can only promise to give my best to help the team."