Jose Mourinho has conceded that he does not know if Diego Costa will be fit for Chelsea's opening Premier League encounter against Swansea City next weekend.
The striker had been expected to feature in the squad for today's Community Shield at Wembley, but he has since been forced to withdraw with a hamstring problem.
When asked about the extent of the damage, Mourinho insisted that he was unaware as to how long it would sideline the 26-year-old.
"I don't know if Diego Costa will be available for the start of the season. He had a little problem after the Barcelona game," Mourinho told BT Sport.
"After that he was training normally and we thought he would be ready, but this morning he was feeling uncomfortable."
In the absence of Costa, Loic Remy has been handed the lone centre-forward's role for this afternoon's encounter against Arsenal, which can be followed live via text updates here.
