Costa is an aggressive and forceful player, and has made an enemy of opponents and opposition fans alike due to his tendency to leave a foot in and occasionally overstep the line of fairplay.
Against Manchester City recently, the forward appeared to be the victim of a well-placed elbow to the head courtesy of Brazilian midfielder Fernandinho.
However, the former Shakhtar Donetsk man escaped any kind of punishment.
In subsequent matches, Costa has been the subject of close attention from referees.
Amidst his many other problems, Mourinho clearly is not happy with the way Costa is being treated by referees.
“I guarantee that if Diego Costa does that it would be a red card; if not, there would be video footage and suspension,” he began, as per the Express.
“I don’t think he is too physical. What I see is him doing his job and no more. Enough time (has passed) to forget his reputation.”
The forward featured for the likes of Braga and Valladolid before moving to Atletico Madrid for a second spell in 2010.
It was here that he enjoyed great success, winning the Liga BBVA title in 2014, the Super Cup in 2010 and 2012 and the Copa del Rey in 2013.
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He also helped Atleti to the Champions League final in 2014.
Last season, he starred for Chelsea during the early portion of the season, before fading, although his contributions in Autumn and Winter were pivotal in helping the Pensioners to the EPL title.