Losing Moises Caicedo would be a problem for Brighton's chances of qualifying for Europe, says manager Roberto de Zerbi.
The midfielder, 21, told Brighton in an open letter he wanted a transfer after bids from both Arsenal and Chelsea.
Caicedo was told by the club to take time off until after Tuesday's transfer deadline, meaning he was absent from Sunday's 2-1 FA Cup win over Liverpool.
"I would like him to finish the season with us," De Zerbi said after the win.
Brighton are sixth in the Premier League, five points behind fifth-placed Tottenham, but with two games in hand on Antonio Conte's side.
"[Brighton chairman] Tony Bloom knows very well my opinion. We lost [Leandro] Trossard and if we also lose Caicedo it's a problem for us if we want to fight for Europe," De Zerbi said.
"If we don't lose Caicedo we are ready to fight."