The Blues' defence of their crown got off to a poor start when they were beaten at home by Burnley on the opening day following an early red card for Gary Cahill, but they have since bounced back with wins over Tottenham Hotspur and Everton.
Courtois expects the likes of Manchester United, Manchester City and Liverpool to be challenging for the title come May, but he is confident that his side can overcome their opening-day defeat to be amongst those contenders.
"The Burnley game was not good, even when we [still] had 10 men. We had a sloppy first half but the second half we were more aggressive and we transferred that into the game against Tottenham," he told reporters.
"They had better chances but we won and we needed to improve against Everton. We knew it would be a hard game but we handled it very well.
"Manchester United have started very well; City have bought in well and I think Liverpool showed [against Arsenal] they are up for the task this season. The Premier League is always hard and we will try to be there until the last day and see if we can retain it."
Chelsea will face Leicester City in their next match after the international break.