Brentford forward Ollie Watkins can leave for offers of more than £18m after a buyout clause in his contract was activated following Tuesday's Championship play-off final defeat by Fulham.
However, Brentford are understood to value the player higher than that.
The clause kicked in when Brentford missed out on promotion to the Premier League, BBC Sport understands.
Crystal Palace lead a number of clubs interested in the 24-year-old.
Palace came close to signing Watkins last season, when the clause was £10m.
Watkins scored 25 goals in 46 Championship games for Brentford this season.
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