Borussia Dortmund insist that Jadon Sancho has no release clause in his new contract but say they are aware of "interest" in the winger.
The 18-year-old has been in fine form for the Bundesliga leaders, who are still unbeaten after seven games, after notching eight assists and one goal in 10 appearances this season.
That form persuaded England boss Gareth Southgate to name the teenager in his squad to face Croatia and Spain later this month, while Dortmund have moved to reward Sancho with a contract extension until 2022.
The club's head of licenced player department, Sebastian Kehl, said this new deal was "without a release clause" as a result of interest in the player.
"We are not naïve to not take note of other clubs' interest," he told Sky Germany.
"The lads are doing a grand job right now. And thus, there will always be enquiries for the players we have here.
"Especially for players like Jadon Sancho, who has been invited to the England senior squad for the first time."
Sancho joined Dortmund from Manchester City last summer, making 12 Bundesliga appearances last season, scoring once and recording four assists.