Ther have been rumors about a reunion between Filipe Luis and Atletico Madrid since the season came to a close, and on Wednesday, Atletico manager Diego Simeone confirmed that he'd have interest in bringing the Brazilian back:
"[Filipe Luis] is a player we like a lot as a kid but who also knows us well and has given a lot to the team. I hope it happens."
Chelsea manager Jose Mourinho has said on several occasions that the Blues are looking to add just 2-3 players to the current group, but I'd have to believe that plan would change should first team players be allowed to leave. While Luis failed to displace starting left back Cesar Azpilicueta, he's the club's only experienced option at left back should the Spaniard become injured, suspended, or just needed on the right, and if he leaves, finding a replacement would become a priority.
The Blues have been linked with a move for Baba Rahman, which would certainly fill the void left by a potential sale of Filipe Luis. It's hard to imagine Chelsea getting anything close to what they paid a year ago for the Brazilian, however, as Atletico Madrid just don't have the sort of financial resources available to make those sorts of moves.