Back in the early 2000s, there were no mobile phones inside FC Porto's bus. No one carrying large headphones either. The players actually had fun together and talked to each other on the road trips across the country in the club's double-decker coach.

And the loudest laughs usually came from the back of the upper floor.

It was the sort of place that made new recruits wonder what was going on back there. They couldn't see it from the front seats—a dark blue curtain separated it from the rest of the bus.

It was a sacred area for some of the biggest personalities on the team, such as Vitor Baia, Deco, Paulinho Santos, Carlos Secretario and Jorge Costa. They called it "the U" because it had a U-shaped seating configuration, with a table in the centre. Porto's captain Costa was in charge, deciding who was worthy to enter.

A bit of everything happened behind that curtain.

"If we tell people many of the things that were done, they wouldn't believe us. Things that others perhaps would not recommend professional footballers do," former midfielder Ricardo Fernandes said in an interview with Expresso newspaper in October.

Among the vices were: playing cards, having beers and smoking cigarettes on the way back from matches. It had always been an area that the coach of the team was forbidden to enter.

Then came a night when one of the kit men told Costa the boss would like to come up. That coach was Jose Mourinho. Mourinho, who was named Porto coach just before his 40th birthday in 2002, became the first boss to enter into "the U," although he immediately urged everyone to treat him like another footballer, one of them.

He showed up a few more times, especially after victories, and was a semi-regular during Porto's winning campaign in the 2003-04 UEFA Champions League.

Mourinho was known as "Ze das Medalhas" ("Ze" being a diminutive of "Jose" and "medalhas" meaning "medals") inside the squad. The players helped him build "The Special One" aura that has followed him through much of his career as they guided Porto to six trophies in two-and-a-half seasons.

The Mourinho philosophy proved wildly successful for those who bought into it, like Maniche, who worked with the now-55-year-old at three clubs—Benfica, Porto and Chelsea.   

"When you are with Mourinho, you are 100 per cent with him; however, those against him are 200 per cent against him. It can be pretty much be summarised like that," Maniche said in December at the launch of his autobiography, for which Mourinho wrote the preface.

"He's still the best coach in the world for me."

It's safe to say the perception of Mourinho being the world's best was not shared inside Manchester United's dressing room by the time he was sacked in December.

Somewhere along the way, he seems to have lost his touch with players. The widely reported breakdown in his relationship with Paul Pogba and other big names ended with the team stuck in an existential crisis. It was the first time Mourinho departed a club before winning them a league title in nearly two decades.

Mentioning his former glories repeatedly in press conferences just highlighted the mire the Red Devils had found themselves in under his guidance.

Despite spending over €400 million on new faces since the summer of 2016, Mourinho was not able to boost his players' morale in the same way he had done with Maniche and others in previous positions.

At Porto, he was famed for his devotion to his players, for going to hospital to watch the surgeries of his players—namely Derlei and Cesar Peixoto—if they were badly injured.

However, the Portuguese coach has now been dismissed around Christmas during his third season at a club in his second consecutive job.

The timing of his most recent sacking will be poignant for Mourinho. He once saw his father, Felix Mourinho—a former goalkeeper and coach who died in 2017—being sacked from a club over the phone during a Christmas-night dinner and has never forgotten the episode.

Since then, he has used it as motivation in his own career.

However, now his career faces a new challenge he is not used to: rebuilding his reputation as one of the world's best coaches. Even in his home country, questions are being raised as to whether he is now a failing manager who is out of step with the times.

"I think Mourinho has lost his 'Midas touch," argues Sergio Pires, a reporter for website Mais Futebol who covers Porto, in an interview with Bleacher Report.

"Only the more uncritical and subservient Portuguese media still rates him as the best manager in the world. Despite holding the best record at United since Sir Alex Ferguson, the investment was colossal for the football he offered in return."

At least once a year, Mourinho leaves the training ground behind and returns to the classroom for a high-performance football coaching post-graduation course he coordinates in Lisbon. He still manages to attract several professionals from every part of the world.

One of the main topics of his class is the concept of "coaches versus anti-coaches."

He explains that coaches are those who can improve their players and teams, while "anti-coaches" can only harm their potential; even though they possess great football knowledge, the "anti-coaches" just can't find the right way to use it.

Has Mourinho gone from coach to uncoach? Rui Malheiro, who has known him since his playing days at Rio Ave in the 1980s, still considers him world class but warns that he has distanced himself too much from the "spectacle football" his sides used to play.

"I believe Mourinho was the best coach around until Pep Guardiola's emergence, which means he dominated the first decade of this century. From Pep on, he has become a 'resultadista' [win-at-all-costs] man who left the spectacle behind in his second, third, perhaps fourth plan," says Malheiro, who works as a football pundit for broadcaster RTP and Record newspaper.

"In the end, I think he wanted to become sort of an 'antichrist,' because the cult of the passing game—finding spaces with the ball, the offensive game—was the basis of Guardiola's ideology.

"For me, he is the best strategist we have ever seen in the history of this sport, but football is not only a tactical battle or a chess game, where the king beats pawns.

"Even in a game where results define the future, the history of football shows—with only a few exceptions—that those who play better football, who have the best game plan and establish an offensive-minded identity, are always closer to success."

It was at Porto that Mourinho became the serial trophy winner he has become known as, even during his ultimately unsuccessful spell with Manchester United. He is the most successful manager of this century.

The decision to leave Portuguese football was taken in a secret lunch with Chelsea owner Roman Abramovich and former chief executive Peter Kenyon at Camelo restaurant, situated in Vigo, Spain, a few weeks before he celebrated the Champions League title with Porto in 2004.

Back then, he still had to chase offers in the market and ask different intermediaries to pursue them. Besides the super-agent Jorge Mendes, he also had former Brazilian defender Jorge Baidek approaching Liverpool on his behalf.

He doesn't need to do that anymore, but it will be difficult to avoid the suspicion that he's no longer the so-called "Special One" wherever he heads next.

"The current Mourinho doesn't belong to the world elite," Tomas da Cunha, a football pundit for broadcaster Eleven Sports, tells B/R.

"It's not because of his last results, which haven't been brilliant, but more because he now finds himself left behind in every aspect that distinguishes a coach: his training methods; his group management and his communication skills.

"Mourinho used to be the master of mind games but now just seems to make enemies in every press conference—inside and outside of the club. United had much more potential [than what they achieved], and it is impossible not to point to Mourinho as one of the main people responsible [for their poor results].

"The 2004 version of Mourinho is done."

Da Cunha argues that, back then, Mourinho was a reference point for many up-and-coming coaches. From his training methods to his relationship with his players, he was universally respected, with his communication skills particularly strong.

"Mourinho handled the expectations and defended his group better than anyone else. Now, he looks like a losing figure and always distant from the players," he says.

In the weekend after his dismissal from Manchester United, Mourinho headed back to his hometown of Setubal and watched his local club, Vitoria, playing against Santa Clara from the stands of the Bonfim Stadium.

It might just be the sort of experience he needs to reinvent himself or, for those who can still see flashes of the old Mou, remind him of what he used to do better than anybody else. Focusing on the players on the pitch and not worrying or complaining about lacking the necessary finances to compete with rivals.

His transfer record at Porto, Chelsea and Inter Milan featured a series of coups, market bargains, players who reached new levels and improved his teams after being discovered in places like Bonfim. His reign at United, on the other hand, was defined by the likes of Paul Pogba, Victor Lindelof, Alexis Sanchez and Fred—expensive signings who ultimately disappointed under his stewardship.

"As we say around here, the Mourinho who guided Porto to the UEFA Cup and Champions League titles was a coach who could make a football player from a broom stub", Pires recalls.

"Back then, he discovered footballers in smaller Portuguese outlets and built great sides around them. He signed players from Uniao de Leiria, Vitoria de Setubal, Boavista, Vitoria de Guimaraes, Belenenses and others.

"His most recent teams have valued individuals over the group. In that sense, the current Mourinho is the antithesis of the man who surprised the whole continent with Porto.

"Despite that, we should never underestimate an intelligent coach who knows everything about football like Mourinho. What is his future? In 2011, when he was in charge of Real Madrid, he said he would never move from Madrid to Malaga—like his predecessor Manuel Pellegrini had done. Even though he has got fewer options now, he can still wait and pick a project that attracts him."

However, it would be a major surprise if Mourinho's next job ended up being in England.

Real Madrid and Inter Milan have been linked with bringing him in for a second spell in charge. Bayern Munich have also been struggling under manager Niko Kovac this season and could be a potential contender for his signature.

"The most important thing for Mourinho to do is to stop and think. It doesn't seem positive for him to remain in the world elite market, with the spotlight on him. Besides that, his best work has always been with projects that needed a new boost: Chelsea and Inter," Da Cunha says.

Malheiro believes he should revisit his first titles to find inspiration: "Mourinho needs to realise that it's time to move back to the past, to a football mentality more offensive and spectacular. That was how he gained an array of fans and became one of the most-talked-about coaches in the world."

Wherever the future takes the Portuguese coach, it will surely be a must-watch story in 2019.

Follow Marcus on Twitter: @_marcus_alves