Diego Costa
Diego Costa may back for the QPR game on Saturday Getty

Chelsea manager Jose Mourinho has received a major boost as summer signing Diego Costa has returned to training.

The former Atletico Madrid striker started the season in a sensational form, scoring nine goals in seven Premier League appearances, but has struggled with numerous fitness problems.

Costa played for Spain in both Euro 2016 qualifiers against Slovakia and Luxembourg earlier this month and has since missed the last three games for his club against Crystal Palace, Maribor and Manchester United.

Before the trip to Old Trafford, Mourinho claimed Costa had a "little chance to play" as the striker had spent a few days in hospital dealing with a stomach virus, while he was slowly recovering from his other injuries.

At the time, Mourinho said: "Diego Costa has a chance, a little chance. Remy no chance, Diego has a little chance, the same [John Obi] Mikel and Ramires. The only one that I can confirm has no chance is Remy."

There was the expectation that the Chelsea manager was prepared to risk Costa for the crucial game, especially considering Loic Remy was also out of action due to a groin injury

However, Mourinho opted to use veteran Didier Drogba instead, which ended up increasing concerns about Costa's injury. But Chelsea have played down the concerns through its official website, revealing the striker has returned to training.

"The latest Blues News bulletin comes from Cobham where the players trained in the afternoon in the wake of the trip to Old Trafford, and prior to heading off again to face Shrewsbury in a cup-tie," Chelsea's official website site stated.

"In the headlines which can be viewed above subject to Fan Club membership, the club's channel reports Diego Costa was outside and involved as part of his ongoing rehabilitation, and there will be more news and live Under-21 match action on Chelsea TV this evening.

Diego Costa may back for the Premier League game against Queens Park Rangers on Saturday 1 November but he is expected to miss the Capital One Cup game at Shrewsbury on 28 October, with Mourinho likely to make plenty of changes to the side that drew at Manchester United on Sunday.