Jose Mourinho revitalised Chelsea as a Premier League and European force when he took on the reins at Stamford Bridge in 2004, and his reputation as one of football's best - and charismatic - coaches has remained.
But why is the Portuguese manager called 'The Special One'? Goal takes a look.
Why is Jose Mourinho called 'The Special One'?
Mourinho's famed moniker dates back to when he arrived at Chelsea for his first spell at Stamford Bridge in 2004, telling reporters in his inaugural press conference that he thought of himself as a "special one" - which has stuck with him in the years since.
"Please don't call me arrogant, but I'm a European champion and I think I'm a special one," Mourinho said.
The manager was not amongst the most famed names in football at the time, though his star had risen after he lead plucky underdogs Porto to a Champions League title in the 2003-04 season.
His self-proclamation caused a frenzied stir within the UK media, as it read as an audacious claim ahead of his first season coaching in the Premier League - but it was a tag that was evidently earned, due to his tactical prowess and excellent managerial skills.
The Special One moniker became even more valid as he enjoyed a successful spell as Chelsea manager, going on to become the club's most trophy-laden coach.
He won back-to-back Premier League titles in his first two seasons in west London, setting the record points total for a Premier League-winning team (95) in his first campaign.
In the years since his first spell at Chelsea, however, Mourinho has endured a mixed bag of success in the Premier League - with his second stint with the Blues never living up to the standards of his first, and a difficult reign with Manchester United one of the low points of his career.
In 2019, when asked about the label and how it has stuck with him in the ensuing years, Mourinho revealed that he had been annoyed with the fact that his coaching talent in English football had been questioned – which is why he proclaimed himself the Special One.
“When I gave my first press conference I was asked if I was ready for the Premier League,” Mourinho told Sky Sports. “I thought: ‘What? I just won the Champions League and you are thinking that I am nobody?’
“So, I went a little bit aggressive by saying I am not one from the bottle, I am a special one. But then, bang, it stayed. No problem.”
The moniker was brought back to attention when Jurgen Klopp joined Liverpool as manager in October 2015, and the German was quizzed about if he would echo Mourinho's self-proclaimed 'Special One' label.
Instead, the German referred to himself as the "normal one."
“I don't want to describe myself," Klopp said in the press conference, laughing.
“The only thing I ask is 'does anybody in this room think that I can do wonders?' No? Let me work. I'm a totally normal guy. I came from the Black Forest.
"I am a totally normal guy, I am the normal one maybe."