Paris Saint-Germain president Nasser al-Khelaifi on Wednesday insisted superstar forward Kylian Mbappe "must sign a new contract" if he wants to remain at the club next season. "The position is very clear. If Kylian wants to stay, he must sign a new contract. We can't let the best player in the world today leave for free. It's impossible," Khelaifi said when asked about the France forward after Luis Enrique was unveiled as the club's new coach. "He said he would not leave for free. If somebody has changed his mind, that is not my fault."