Paris Saint-Germain president Nasser Al-Khelaifi is "200%" certain Kylian Mbappe will remain with the club but appears to have questioned the commitment of Neymar.
The world's two most expensive footballers have been heavily linked with moves away from the Ligue 1 champions this summer.
Al-Khelaifi is no longer willing to tolerate players acting like "stars" at Parc des Princes and says "nobody forced" Brazil forward Neymar to sign from Barcelona for €222m in 2017.
But he is adamant France World Cup winner Mbappe, who initially joined on loan from Monaco two years ago before moving permanently for €130 last summer, will stay in Paris.
"I want players proud to wear our jersey, not players who do the job when it suits them," Al-Khelaifi was quoted as saying on francefootball.fr in an interview will be published in full on Tuesday.
"And if they do not agree, the doors are open. Ciao. I do not want to see stars any more."
Speaking about Mbappe, he said: "Will he still be at PSG next year? I am not 100 per cent sure, but 200 per cent! I will not let go of this player."
Asked about Neymar, who, like Mbappe, has a contacted until 2022, Al-Khelaifi added: "I want players willing to give everything to defend the honour of the jersey and to join the club project.
"Those who do not want, or do not understand, we see each other and we talk to each other.
"There are of course contracts to be respected but the priority now is total membership of our project.
"Nobody forced him to sign here. Nobody pushed him. He came knowingly to join a project."