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Chelsea striker Diego Costa was "totally depressed for a month" after he reversed over his pet Yorkshire Terrier and killed it.

The incident occurred during the Spain international's time as an Atletico Madrid player between 2010 and 2014.

In an excerpt from a newly released biography about the forward, entitled 'Diego Costa: The Art of War', Costa's Atleti teammate Paulo Assuncao revealed the effect the dog's death had on him.

“Diego brought his Yorkshire Terrier to Madrid but one day when he was parking and didn’t realise the dog was behind the car, he reversed over it," said Assuncao.

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"He was devastated, totally depressed for a month. When I asked him why he was so low he practically broke down.

"He said: ‘I can’t believe it. I killed my dog. He came out of the house to greet me and I didn’t see him and I ran over him.’”

Costa, 26, is a doubt for Chelsea's Community Shield clash with Arsenal this weekend.

Jose Mourinho revealed the striker felt a twinge in his hamstring during the Blues' pre-season friendly penalty shootout win over Barcelona.