Jose Mourinho has confirmed that Thibaut Courtois requires surgery on a knee injury sustained earlier this week. Although he did not specify exactly how long Chelseas first-choice goalkeeper is expected to spend on the treatment table, it was predicted that he will be out for quite a long time in what will come as a major blow to the defending champions after their sluggish start to the 2015/16 Premier League season.

The towering Belgium international featured twice for his country during the recent international break, starting the Euro 2016 qualifiers against Bosnia and Herzegovina and Cyprus before suffering the problem upon his return to training at Cobham. Initial reports from the London Evening Standard suggested he may have avoided damage to his cruciate ligaments, while Spanish publication AS claimed that surgery had already taken place at the Clínica Quirón in Barcelona and estimated that Courtois could be missing until early 2016.

No injury problems from national teams, but Courtois injured in training. Cannot tell you much but needs surgery, Mourinho was quoted as saying by The Mirror at a press conference held before Chelseas trip to Everton on 12 September.

As a consequence of that hell be out for quite a long time. I cant be more specific now. Its a big blow, but... you will not see me next week speaking again about Thibaut. I never do when player is injured. Its not easy to have the best goalkeeper injured, but its easy to have one of the best to play, and we have Begovic. We have a top goalkeeper and Begovic will play.

Begovic, who joined Chelsea from top-flight rivals Stoke in an £8m ($12.3m) deal back in July, has already stepped into the breach twice already this season after Courtois was shown a red card for a late challenge on Bafetimbi Gomis during the 2-2 draw against Swansea on opening day. As well as appearing as a 54th minute substitute in that match, the Bosnian also started in the subsequent 3-0 defeat to Manchester City.

Beyond Courtois and Begovic, Chelseas current goalkeeping options begin to look a little thin. Academy graduate Jamal Blackman made just one solitary appearance during an unsuccessful loan spell under Aitor Karanka at Middlesbrough last term during the Championship outfits Capital One Cup defeat to Liverpool, although he was listed among the Blues substitutes at the Etihad Stadium. Mourinho confirmed that the 19-year-old will now become chief deputy.

The third goalkeeper is always a complicated situation because it can be that you dont sit on the bench once all season, he added. In my first spell here, Hilario was third choice and he played against Barcelona in the Champions League.

Our decision was the third goalkeeper would be a young English goalkeeper behind two fantastic goalkeepers and we think thats a normal situation. Now Jamal [Blackman] becomes the second. He was on loan at Middlesbrough and didnt play once in the Championship. He has no experience but he has potential. I just lost a goalkeeper, I want to be positive.