Courtois will have ambitions to eventually dislodge Cech when he returns from a second season on loan with Atletico Madrid next year, but his senior colleague is ready for the challenge.
"In big clubs they are always buying top players for every position, it is up to you to keep your place," said Cech.
"When the moment comes it will come, but I believe I have a lot to offer and I will try and keep my place for another four years."
Cech, who will have spent a dozen years at Stamford Bridge if he sees out his deal, added in The Independent: "When I joined I tried to gain my place in the starting XI, to play as much as possible and win trophies, but I was not thinking I could be at Chelsea for 12 years.
"The club is a big part of my life and I am very happy there."