Chelsea striker Diego Costa has reportedly suffered an injury blow in training, prompting concerns that the summer arrival could be out of action for around six weeks.

The Spain international has started his Chelsea career strongly by scoring twice in the club's opening two Premier League victories after moving from Atletico Madrid this summer.

However, according to The Telegraph, the 25-year-old's run could be halted after he picked up a hamstring problem on Wednesday.

While there have been suggestions that the striker could be sidelined for more than a month, reports have claimed that Chelsea are hopeful that further tests will prove that the injury is not as bad as first feared.