Jose Mourinho has conceded that he is unsure whether Chelsea striker Diego Costa will be fit to face Swansea City on Saturday.

The Blues begin the defence of their title at home to Garry Monk’s outfit but last season’s 20-goal forward continues to be troubled by his hamstrings.

Costa played no part in Chelsea’s Community Shield defeat to Arsenal at Wembley last Sunday having aggravated his hamstring against Barcelona in a friendly in the United States.

Mourinho revealed his concern over the fact Costa ended last season carrying an injury and returns for the start of the new campaign no better off.

“Costa is not ready. It is not a good feeling for him, it is not a good feeling for me,” Mourinho told reporters. “I have to be honest and say that it is a bit of a concern.

“A player that didn’t finish the season and (then) doesn’t start the season obviously doesn’t make me happy.”

Mourinho praised the 26-year-old for his work in attempting to get fit but he appears to be growing frustrated at the seemingly endless speculation over Costa’s fitness in the run up to games.

The Portuguese was not drawn on whether he will be searching for another striking option before the transfer window closes.

He says he has enough at his disposal to cope with the challenge of Swansea at Stamford Bridge which is his primary concern.

“In this moment, the only thing I want to do is play against Swansea. The squad is good enough and big enough to play against Swansea,” Mourinho said.

Costa is 6.50 to be leading goalscorer in the Premier League this season while Chelsea are 2.63 to retain their title.