Courtois has expressed his desire to play for Chelsea but will only return if he is given first team assurance.
While Petr Cech has still a quality to play for Chelsea for atleast two years but keeping him as a first choice stopper will give Courtois a clear reason to leave Chelsea on permanent basis and Atletico Madrid are looking for an opportunity to sign him permanently.
Cech shared the Golden Glove last season with Arsenal goalkeeper Wojciech Szczesny. The 32-year-old has played 470 games for Chelsea in 10 seasons.
A return of Belgian might make Cech to move to a new club.