Chelsea are growing increasingly fearful that they will lose key defenders Antonio Rudiger, Andreas Christensen and Cesar Azpilicueta for nothing in the summer, 90min understands.
The Blues find themselves in a situation where all three first-team players are out of contract at the end of the season and the club's hierarchy are struggling to agree fresh terms with each of them - although they have managed to tie veteran centre-back Thiago Silva down for another year.
In each case, 90min has been told the sticking point is either the disparity between Chelsea's terms and the player's wage demands, or the emergence of better offers from elsewhere.
With just over five months remaining for the west London club to find a solution some of Europe's biggest clubs are inevitably beginning to circle, enticed by the opportunity to secure at least one top class defender without having to pay a transfer fee.
90min revealed last month that Chelsea are now resigned to losing Rudiger on a free transfer in 2022 - and that stance hasn't changed. Talks over a new deal have long been at an impasse, with the Blues' most recent offer well short of matching the German's desire to become one of the club's highest-paid players.
The 28-year-old has completely overhauled his reputation as something of a liability in a stellar 12 months under head coach Thomas Tuchel and has inevitably emerged as a target for essentially all of Europe's biggest clubs.
Having been sanctioned for changing his demands earlier this season, sources have told 90min that Denmark international Christensen - another to have enjoyed a rise to prominence under Tuchel - is now comparing Chelsea's most recent contract proposal to the ones he has received from elsewhere. It is understood the most lucrative of those arrived from Barcelona.
Camp Nou could well be Azpilicueta's destination, too. As reported by Spanish journalist Jose Alvarez Haya, 90min understands Barça have tabled a three-year contract for the Blues' versatile club captain - which surpasses Chelsea's offer both in length and financially.
A source has said Barcelona are quietly confident of completing both deals.
Chelsea are now facing up to the possibility of losing all three defenders at the end of season and are making plans for that eventuality.
90min reported earlier this month that Chelsea remain determined to sign Sevilla's Jules Kounde after failing to land him last summer and there is a belief within the club that he will join at some point in 2022. The Frenchman is unwavering in his desire to move to Stamford Bridge and he has reiterated that to his current employers.
Bayern Munich's Niklas Sule - another centre-back who is out of contract at the end of the season - is another name under consideration.