Chelsea have reportedly taken measures to extend the contract of Ian Maatsen amid interest in his signature.
The Dutchman has spent much of his time at Stamford Bridge representing EFL clubs on loan, with his most recent stint coming at Burnley in the Championship last season.
His performances at Turf Moor led to the Netherlands Under-21 international being handed an opportunity to impress during pre-season by head coach Mauricio Pochettino.
Maatsen delivered on that front, starring in Chelsea's games in the United States, but he has since had to play a bit-part role since the beginning of the campaign.
Although two starts have been made in the EFL Cup, Maatsen has accumulated just 84 minutes across six matches in the Premier League, helped by injuries to other players.
While Maatsen rejected a permanent move to Burnley in the summer, he has also shown a lack of willingness to pen fresh terms with the West Londoners at a time when his future is up in the air.
That has led to a wide array of interest from high-profile clubs who are sensing an opportunity to sign a highly-rated young player on a free transfer.
Manchester City, West Ham United and Barcelona are all said to be monitoring any developments with Maatsen as they plot a move in January or next summer.
However, according to the Evening Standard, Chelsea officials have taken the step of activating a 12-month option in the player's contract.
The report indicates that co-owners Todd Boehly and Clearlake Capital had preferred to hand Maatsen a new contract with a wage rise, rather than trigger the previously-agreed clause.
Nevertheless, in order to protect their position, Chelsea now have the 21-year-old on a contract until 2025, effectively ruling out a sale until next summer at the earliest.
Maatsen is aware that Chelsea would have been happy to sell him for £31m during the summer had he wanted to spend another period at newly-promoted Burnley.
Pochettino is expected to select Maatsen on the substitutes' bench when Chelsea play host to Arsenal in the Premier League on Saturday evening. body check tags ::