Will Tottenham be getting a mellowed manager, rather than the one who stoked internal feuds at Chelsea and Manchester United?

Mourinho's exile from management ended after being appointed on Wednesday by Tottenham within 12 hours of the announcement of Mauricio Pochettino's firing.

"I couldn't be happier and look forward to the challenge," Mourinho said in a video released by Tottenham. "What can I promise? Passion, real passion.

"Passion for my job, but also passion for my club, that's the way I have been all my career and I want to try, obviously, everything to bring happiness to everyone who loves the club."

Mourinho has always delivered happiness in the form of trophies and title successes. But several of his stints have also seen the atmosphere around the team sour as his relationship broke down with club officials, players and even fans.

There was the "palpable discord" that curtailed Mourinho's second spell at Chelsea in December 2015.

A turbulent 2½-year spell followed at Manchester United that ended in December 2018 when the club tired of the volatile coach constantly picking fights and criticizing his own players as the team struggled.

But he won three Premier League titles during his two spells at Chelsea, and lifted the Europa League trophy as the highlight of his time in Manchester.

He now arrives at a club without a track record of winning titles, with no trophy lifted since the 2008 League Cup.

While Pochettino transformed Tottenham, achieving an unprecedented four consecutive Champions League qualifications as the team rose in status, a trophy eluded the Argentine during his 5½-year stint.

He led the club to its first Champions League final last season, only to lose to Liverpool. Rather than being a springboard for a sustained challenge in the Premier League to deliver Tottenham's first championship since 1961, Pochettino sounded increasingly unsettled.

Having said on the eve of the Champions League final he could choose to walk away from Tottenham, that decision was taken out of Pochettino 's hands 173 days later when he was fired on Tuesday night.

Tottenham's improbable run to a first European Cup final masked a drop-off in form in the Premier League that has seen the team win just six of its 24 games since February, straddling the end of last season and the start of this season.

Tottenham chairman Daniel Levy said he turned to Mourinho to bring "energy and belief" back to the club.

"He has a wealth of experience," Levy said, "can inspire teams and is a great tactician."

Mourinho takes charge of Tottenham for the first time on Saturday at West Ham with the team 14th in the Premier League after 12 games, 11 points off the four Champions League qualification positions where Tottenham grew accustomed to finishing under Pochettino.

"It's a privilege when a manager goes to a club and feels that happiness in relation to the squad he is going to have," said Mourinho, who oversaw his first Tottenham training session on Wednesday.

Since leaving Porto for Chelsea in 2004, Mourinho has always worked at clubs with big budgets so Tottenham is not necessarily a natural fit.

Pochettino had to battle against the biggest teams in Europe while working with strict financial constraints, particularly as Tottenham prepared to move into its new stadium last season.

The club has prioritized developing young talent from within the academy, including striker Harry Kane and midfielder Harry Winks, and Mourinho knows he has to follow the same philosophy.

"There is not one manager in the world who does not like to play young players and help young players to evolve," Mourinho said. "The problem is sometimes you get into clubs and the work that is below you is not good enough to produce these players."

Tottenham's players will certainly respect Mourinho's resume, which also includes league titles with Porto in Portugal, Inter Milan in Italy and Real Madrid in Spain. He has won the Champions League with two clubs, Porto in 2004 and Inter Milan in 2010.

It is Mourinho's man-management that has mostly been questioned in the latter years of his coaching career, given his penchant for publicly criticizing his own players.

The 56-year-old Portuguese is surrounded by a new coaching staff at Tottenham, with Joao Sacramento and Nuno Santos joining from Lille.

Mourinho signed a contract to the end of the 2022-23 season with Tottenham but has never spent more than 3½ years in a single stint at one club.

While Mourinho says Tottenham has "good players that the majority of the big clubs in Europe would be looking for", the squad needs a revamp after growing stale because of the lack of recent recruitment.

He will need to quickly fix Tottenham's leaky defense and get more out of the team's underperforming midfielders, Dele Alli and Christian Eriksen.

The main playmaker, Eriksen appeared to be on his way out of the club as he seeks a new challenge but working under Mourinho might offer that.

Mourinho, who still has a house in London, will be back coaching the Champions League next week, too, with Tottenham needing one win from its final two group-stage games to qualify for the knockout stage. The team is out of the English League Cup, having been eliminated by fourth-tier Colchester in one of a number of humiliating results under Pochettino this season.