Chelsea manager Jose Mourinho has revealed that he does not know if Diego Costa will be fit enough to start the first game of the Premier League season.

The Spanish striker suffered a hamstring strain in training ahead of the Community Shield last week and played no part in the Blues' pre-season loss to Fiorentina.

When asked how likely Costa was to play at the weekend, Mourinho told Sky Sports News: "I have no idea. We have two other strikers. One to play and one on the bench."

Chelsea start the defence of their title against Swansea City on Saturday.