Chelsea striker Diego Costa was left "depressed" after accidentally running over and killing his pet Yorkshire Terrier, according to former Atletico Madrid teammate Paulo Assuncao.

The incident, which has been brought to light in new book Diego Costa: The Art of War by Fran Guillen, occurred between 2010 and 2014.

Assuncao has revealed that Costa reversed over the dog without realising that his pet had come out of his home in Spain to greet 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," Assuncao is quoted as saying.

"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.'"

The book also reveals that Chelsea convinced Costa to reject a move to Liverpool in 2013 and instead wait for a switch to Stamford Bridge a year later.