Barcelona are reportedly hoping to sign Chelsea's defensive trio Andreas Christensen, Cesar Azpilicueta and Antonio Rudiger this summer.
All three players will see their contracts expire at Stamford Bridge in June, and they are now free to negotiate pre-contract agreements with foreign clubs.
Chelsea are currently unable to renew the contract of any first-team players or staff while sanctions on owner Roman Abramovich are in place, meaning that the futures of their out-of-contract stars are at risk.
Barca are understood to have already finalised a deal to sign Christensen as a free agent this summer, along with AC Milan's Franck Kessie, but the Daily Telegraph claims that the Catalan giants also want to lure Azpilicueta and Rudiger to Camp Nou.
Chelsea are believed to have extended Azpilicueta's contract by 12 months, with negotiations having taken place ahead of the sanctions, but Barcelona are prepared to offer the 32-year-old a two-year deal, with the option of an extra year, to try to convince him to return to his native Spain.
As for Rudiger, the report adds that the player's brother and agent has been seen entering a hotel in Catalonia, along with Barca chiefs Mateu Alemany and Jordi Cruyff, to hold contract talks.
Chelsea boss Thomas Tuchel has recently told reporters that there is a "very high possibility" that Azpilicueta will remain at Stamford Bridge this summer, and the German is also "confident" that Rudiger will stay put in West London.