London - Jose Mourinho talks bluntly, wins big and then everything seems to go wrong.
WATCH: Mourinho's first interview as Man United manager
Manchester United confirmed the that the Portuguese penned a three-year deal which will see him at the club till at least 2020.
The 53-year-old Portuguese has won eight league titles in four countries with Porto, Inter Milan, Real Madrid and Chelsea as well as two Champions League titles with Porto and Inter Milan.
But Mourinho has also been ordered out or walked out in various ways when ambition or tensions have taken over.
Building a legacy is an unsolvable puzzle for the man whose remarkable record earned his "Special One" nom de guerre.
Mourinho's second stint at Chelsea, which ended acrimoniously in December, summed up his career: a period of bedding in, one or two seasons of stunning success and then things fall apart.
"Mourinho burns out his players after a year and a half, at most two years," said former AC Milan and England coach Fabio Capello just before Mourinho's Chelsea exit.
Mourinho is never short of job offers however. His tactical acumen, attention to detail and ability to form water-tight bonds with players have made him one of the greatest coaches of all time.
Mourinho has no record as a player. And his brash, arrogant style may not sit easily with everyone. But after working as assistant to Louis van Gaal -- whom he succeeds at United -- and having unremarkable spells at Benfica and Uniao de Leiria, he emerged as a world-class leader at Porto in 2002.
Porto beat Manchester United on the way to winning the Champions League in 2004 and Mourinho was soon on his way to Chelsea.
"Please don't call me arrogant, but I'm European champion and I think I'm a special one," he declared at a press conference on joining the London club financed by Russian tycoon Roman Abramovich.
'THE MOURINHO AURA'
"Mourinho was the best. For me he was. He brought my confidence to a level it had never been," said Chelsea great Frank Lampard, who blossomed under Mourinho into one of Europe's finest goal-scoring midfielders.
"It's a presence and an aura and a way with people. He galvanises people. His own self-confidence reflects back on his teams."
Two Premier League titles followed but there was no European success and friction with Abramovich mounted.
Mourinho left abruptly in September 2007 and appeared in June the next year as coach of Internazionale. In his first season, Inter, with Zlatan Ibhrahimovic in the frontline, won the Italian title but lost to Manchester United in the Champions league.
He had stormy relations with Italian journalists - whom he once accused of "intellectual prostitution" - and his rivals. Catania president Pietro Lo Monaco called Mourinho a "big mouth".
But the Portuguese became an Inter legend in 2010 when they won Serie A, the Italian Cup and beat Bayern Munich 2-0 in the Champions League final.
Within a week of the European triumph, Mourinho was on the move again to start three boom and bust years at Real Madrid. The team won a Spanish title and the Copa del Rey but relations with star player Cristiano Ronaldo were difficult and Real never hit the heights.
The Portuguese left Madrid by "mutual agreement" just days after the end of what he called "the worst season of my career" in May 2013.
In less than three weeks, Mourinho had signed again for Chelsea.
His first season back saw Mourinho finish a campaign without a trophy of any description for the first time in his managerial career, but he reshaped the team brilliantly.
In came Thibaut Courtois, recalled from a loan at Atletico Madrid, Cesc Fabregas and Diego Costa, and with a galvanised spine Chelsea swept to the league title and beat Tottenham Hotspur in the League Cup final.
Mourinho said that Chelsea's title success vindicated his decision to return to "the most difficult league in Europe", but seven months later, he was gone.
The Mourinho strategy completely unravelled in the early weeks of the 2015-16 season.
Overwhelming favourites to retain the title, they lost nine of their first 16 league games and slumped to 16th place in the table.
Mourinho received trenchant criticism for sidelining team doctor Eva Carneiro, who left the club after being publicly lambasted by the manager for running on to treat a player at a vital moment in a game.
It recalled other dark episodes from Mourinho's past - the hounding of referee Anders Frisk in 2005, the eye poke on Barcelona assistant coach Tito Vilanova in 2011 - and left him with more stains on his reputation.
"Will he be loved?" former Liverpool and England defender Jamie Carragher asked last year. "Chelsea fans undoubtedly adore him. Porto and Inter (Milan) supporters will, too. Yet beyond that? It is debatable."
Now he joins another great club in need of rejuvenation. Only time will tell whether the Mourinho magic will last longer this time.