The 22-year-old Belgian spent the previous three seasons on loan at Atletico Madrid, but has now taken over from Petr Cech as Jose Mourinho's preferred option between the posts.
Courtois, currently away on international duty, expects to put pen to paper on a new long-term deal with Chelsea when he returns to England.
"It’s not yet signed. I am here [in Belgium] with the national team so it is difficult, but when I am back at Chelsea I will probably sign the new contract," he told Sky Sports.
Courtois has sympathy for rival Cech, who has found himself on the bench this season after 10 seasons as a regular starter.
"We don’t talk about the situation, but of course I know he has played 10 years at Chelsea and that now I am playing and for him it’s not the nicest situation," added Courtois.
"But that is the decision of the board and the trainer.
"He is working hard in training to be ready when I cannot play or I am maybe not playing well. We work well together.
"As a professional and a winner you always want to play every game, so we will see what the decision is of the coach. But of course I am a professional player and I want to play every game that is possible.”
