Diego Costa injury: Chelsea striker 'punched himself', says Jose Mourinho, and could be a doubt for Liverpool clash

Diego Costa is an injury concern for Chelsea's crucial Premier League match against Liverpool at the weekend after he lasted just 30 minutes in the League Cup exit at Stoke City.

The Spanish striker had to be sent to hospital after colliding with Stoke midfielder Charlie Adam and suffering pain to his back and rib.

It's not yet clear how long Costa, who clutched his side while waving for medical staff, will be out for.

Chelsea are likely to offer an update at some point today.

When asked about the injury, Chelsea manager Jose Mourinho was unsure of its severity.

"He is in the hospital - I don't know," said the Portuguese, who also blasted Chelsea's critics for suggesting he had lost the dressing room.

Mourinho said he didn't know if Costa would return for the Liverpool match.

He then added, jokingly: "I think he punched himself."