The Belgian international moved to Chelsea in 2011, but was quickly sent on loan to Atletico. He's spent 18 months in the Spanish capital, and is yet to play a single game for his parent club.
The 21-year-old will remain on loan with Diego Simeone's side until the end of this season, but reports have suggested Atletico Madrid are keen to bring him to the Vicente Calderon on a permanent basis.
But Chelsea view Courtois as a long-term replacement for Petr Cech, and are not willing to sell him this summer.
As a result they've slapped a £17m asking price on the goalkeeper - more than double the fee they paid Genk.
But the report claims Atletico are even willing to negotiate a potential transfer for Radamel Falcao with Chelsea, and want Courtois as part of the deal.
Falcao has been a long-term target for the Stamford Bridge club, and the La Liga striker is widely regarded as one of the best forwards in the world.
But Chelsea are believed to be unwilling to consider including Courtois as part of any deal for the Colombian international.
The Belgian international is reportedly willing to stay on loan at Atletico Madrid for a third season, and with Cech still established as Chelsea's number one, the Blues may explore this option.
Courtois is a fan favourite at the Vicente Calderon. Last season he helped the club win the Europa League, and this term he broke the La Liga record for most minutes without conceding a goal at the Calderon.
Courtois played on past Abel Resino's impressive 800-minute mark that had remained unbeaten since the 1990-91 season.