Diego Costa injury overshadowing Chelsea's start to season

Costa had reportedly been fit ahead of the Community Shield on Sunday, with Mourinho claiming that he was ready to play.

But the Chelsea manager's words proved to be incorrect: Costa missed the game with the hamstring problem that plagued him last season and continues to perplex Mourinho.

"I don't know," Mourinho said after the match when asked if his star striker would be fit next weekend.

"You think I'm lying but I'm not lying.

"If next Friday you ask me does he play against Swansea, I don't answer, because maybe yes, maybe no. I prefer not to answer. Let's see."

Costa's injury woes with the Blues last season, and indeed his similar persistent trouble during his final campaign with Atletico Madrid the year before, will be a serious cause for concern for Chelsea. Costa hit the ground running last term and got Chelsea into a superb position before injury struck, but if he is not about or is at less thatn 100 per cent for the first few games of the season then the Blues could find themselves with a lot of catching up to do.