Jose Mourinho: 'He loves, he fights' Don Riddell and James Masters, CNN

He's known as "The Special One," but now one of Chelsea's star players has revealed a more complex picture of Jose Mourinho. Diego Costa, the English Premier League champion's leading goalscorer last season, says the Chelsea manager has a softer side which few outside of the locker room ever get to see. "He is a person that lives, loves, fights and works -- he is always trying to improve," Costa told CNN when asked about the 52-year-old. "He is that person that you see with the ambition to be victorious, the ambition to win, the ambition to become better. "That is a point that makes the difference -- that ambition to be better than you were last year." Mourinho led Chelsea to the English title last season after returning for a second spell in charge at Stamford Bridge in 2013. The Portuguese coach is one of the most successful in the game having won two European Cups --first at Porto and then at Inter Milan -- while he has claimed domestic league titles in England, Italy, Spain and his native Portugal. While Costa talks about Mourinho's more genial nature and his "friendship" with players, the Chelsea manager is not without his detractors and the Portuguese's behavior outside of the home locker room has often been criticized. His touchline spats and arguments with referees are well documented, notably an incident with the late Tito Vilanova -- the former Barcelona manager -- who Mourinho poked in the eye after an argument during his time at Real Madrid. No stranger to controversy himself, Costa refrained from commenting on Mourinho's past transgressions, instead preferring to praise his coach's more personable nature.