Chelsea boss Mauricio Pochettino cannot guarantee a new deal for Conor Gallagher.
The midfielder has captained the team in Reece James' absence this season.
West Ham and Tottenham made attempts for Gallagher over the summer, while Everton had an offer accepted in January before Gallagher turned down the move.
But asked about a new contract for Gallagher, Pochettino said: "It is like a marriage between the player and club, both sides need to feel good and that is why this moment you can arrive at a new deal.
"Even if you want to extend the contract, you stop and speak. Of course, he is a player that is doing fantastic. We are so happy with how he is doing."