Newcastle United have made Mauricio Pochettino question himself before.

Tottenham's now-infamous 5-1 defeat at St James' Park on the final day of the 2015-16 campaign cost them second place in the Premier League and launched a period of deep introspection for their manager. It was a moment of such desolation that Spanish journalist Guillem Balague chose it as the inauspicious starting point for his book "Brave New World," chronicling Pochettino in his own words as he began a journey that would take Spurs to a Champions League final just three years later.

In doing so, through a mixture of innovative high-energy football and powerful team spirit, all on a modest budget, the 48-year-old became one of the most sought-after managers. And yet, after counting Real Madrid and Manchester United among his potential suitors, Newcastle now looks his most likely destination, with the club's £300 million Saudi-backed takeover only requiring ratification from the league.

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As revealed by ESPN, Pochettino is their first choice to replace Steve Bruce. Appointing Pochettino -- on a contract worth a reported $23m (£19m) per year -- would be a remarkable coup and a statement of intent from controversial would-be owners aiming to jolt a sleeping giant to life.

Opposition to the deal persists within the British Parliament, with calls growing this week to block the deal due to the involvement of the Saudi Arabia Public Investment Fund. The country's poor human rights record has been cited, while there are demands from members of Parliament to hold an evidence session on Saudi-based piracy of British sport. However, the government has so far suggested it will not intervene, suggesting Pochettino could soon have a big decision to make.

Pochettino is sufficiently attuned to the wider world to factor these issues of morality into his thinking. In pure football terms, would trying to revive the fortunes of a mid-table club in disarray -- albeit on a limitless budget -- really be the right step for a man who had the world at his feet just 12 months earlier?

Pochettino famously keeps a tray of lemons in his office because he was once told by a friend that they absorb negative energy. Now ruminating on his future in his north London home, it might feel as if he is comparing apples and oranges.

There was a period where it felt almost inevitable that Pochettino would land an elite job, even after his five-year Tottenham tenure unravelled to such an extent that he was sacked in November and replaced by Jose Mourinho in less than 12 hours. Few sacked managers emerge from such situations with as much credit as Pochettino. That is a testament to the work he did in defying conventional sporting wisdom that inextricably links financial expenditure with results. There was no trophy to show for it, but everything else: a squad with no signings throughout the 2018-19 campaign, compromised further by injury and playing most of the season away from home, reached Europe's biggest game against all the odds. They also secured a fourth consecutive top-four finish in the Premier League, the club's best run since 1964.

Pochettino enjoyed a close working relationship with chairman Daniel Levy, but tensions that grew near the end provide pointers as to why he might be tempted by a project like Newcastle.

Despite public denials, Pochettino and Levy had significant disagreements over the lack of investment in players. The former hinted at such in a series of news conference utterances, decreasingly coded as the frustration grew, about "thinking big" and going to the next level as a club. The inference was clear: Pochettino had bought into Levy's financial prudent model but that could only ever take a club so far against the largesse of Manchester City, Chelsea and the rest.

Liverpool, who defeated Spurs in that European final, had already recognised that reality by sanctioning big-money moves for Alisson and Virgil Van Dijk. Tottenham would either have to match that ambition or a faltering club historically operating at that level would sense an opportunity to prise him away. Manchester United and Real Madrid were -- and indeed, remain -- two such examples.

Like many top managers, Pochettino isn't particularly prone to giving interviews beyond the standard requirements, and so it was particularly telling that as far back as November 2017, he began subtly courting the Madrid press. Publicly, there were 100% denials he was interested in the Real job; it can be taken at face value contemporaneously, but Pochettino might well have had one eye on the future.

Managers are obliged to hold prematch and postmatch news conferences around Champions League games. They are "all-in" affairs, meaning only broadcast rights-holders speak to them in addition to this main briefing. Yet in both London and Madrid, Pochettino willingly held court in an impromptu huddle with Spanish journalists, conducting a series of additional, unplanned interviews with locals only too willing to link him with a move to Spain. Nothing untoward was said, and Pochettino remained respectful of his employers, but there were figures at Spurs who privately noted the voluntary exposure as something that would, at the very least, do his reputation no harm in the Spanish capital.

Fast forward to last month, and a BT Sport interview in which Pochettino reiterated his desire to return to management when the coronavirus pandemic allows, while also simultaneously expressing his enduring love for Tottenham. Regarding the latter, there's no reason to doubt his sincerity. His affection for the club is genuine and is not sullied by the manner of his departure. But one senior figure at Tottenham who worked with Pochettino told ESPN they interpreted that interview as "paving the way for taking another job in England by squaring it with the Spurs fans."

For a long time, it seemed likely that Pochettino's next destination in England would be Manchester United. Ole Gunnar Solskjaer's transition from panacea to pariah at Old Trafford made the Spurs manager's pedigree stand out even more. Pochettino is an admirer of Sir Alex Ferguson's -- the pair have previously dined together -- and the prospect of both United's status and financial might would obviously appeal to a manager with palpable aspirations of scaling the summit.

Levy knew United's pull as early as 2016. Around the time Pochettino was reflecting on that thumping defeat at Newcastle, United sounded him out over replacing then-manager Louis van Gaal. After the Argentine chose to stay at Spurs, Levy rewarded him by delivering a £156,000 Bentley Bentayga to his house.

Pochettino has similarly been earmarked as a possible successor to Pep Guardiola at Manchester City when his deal expires in 2021. Yet while Solskjaer continues to cling on, City are hopeful Guardiola could yet commit beyond next year.

If England is his preferred choice, a financially supercharged Newcastle might appeal, but Pochettino has to believe there is substance to the challenge.

Pochettino ranks the Netflix drama "House of Cards" among his favourite boxsets. He claims to have learned much from the show's Machiavellian male lead, Frank Underwood, but is far less cynical by nature.

"I take pleasure in the journey," Pochettino wrote in "Brave New World," the 2017 book about his work at Tottenham. "I only know of one path to the top of this profession: enjoying your work, being flexible and willing to evolve, and finding time to be alone and think creatively ... although it is getting increasingly difficult. But we all play to win.

"Anyone who says otherwise is lying. I hope I don't change my tune when I win trophies. If I do, I'll be a successful coach, but I'll have lost moral authority."

There is an inevitable appeal of a seemingly unlimited transfer budget, but Pochettino has always been somewhat ambivalent to success achieved through those means. In May, he said: "Would I like to be a [Manchester] City or a Liverpool? To some extent yes and to some extent no. I prefer to fight for something historical, unique."

Newcastle does have a rich history of its own with a loyal and fervent fanbase. Pochettino would find a kindred spirit in the region's devotion to football, but taking the job would also require an explanation of his moral compass and an ongoing public relations role defending the owners' background. (The mooted £19m salary would provide ample compensation.) According to French publication L'Equipe, it would be a wage bettered only by Diego Simeone at Atletico Madrid and Guardiola, but money with autonomy would tempt him even more.

There's no suggestion Levy ever infringed upon Pochettino's authority on football operations at Tottenham, but his strict budget controls and tough negotiating positions had a significant impact on the head coach. For example, sources have told ESPN that 12 Spurs first-team players were made available for sale last summer in a list circulated among select agents. The move was part of a plan to generate income, but also streamline a squad Pochettino wanted to take to that "next level." However, less than half of those ended up leaving the club as Levy failed to follow through, creating ill feelings and resentment within a group that had, for so long, pulled together to become more than the sum of its parts.

There was also a widely held belief that opting not to sign new players allowed those already at the club to lax into a comfort zone, thus making Pochettino's job harder still and reneging on an agreement that convinced him to commit his own future to the club.

"The models at Liverpool and City involve giving the respective managers the autonomy to manage the sporting side of the game whichever way they like," Pochettino wrote in his book. "Coaches aren't given that freedom at Chelsea, Spurs, Arsenal."

It remains to be seen whether he would get that at Newcastle, but a large budget with minimal oversight is the antithesis of how conditions were at Tottenham. The post-coronavirus world will stretch even the top clubs.

In "House of Cards," Underwood highlighted the difference between money and power. "Money is the McMansion in Sarasota that starts falling apart after 10 years," he began. "Power is the old stone building that stands for centuries."

If Pochettino is given both at Newcastle, the combination could be irresistible.