LONDON • Every so often, the lights go out on Mauricio Pochettino. The Argentinian, who has transformed Tottenham Hotspur into contenders for the Premier League title and, in the process, become the accidental saviour of English football, keeps long days.
He rarely arrives at his club's training ground after 7.15am. Only occasionally does he manage to escape before 7pm.
There are days, though, when he stays later still, poring over footage of the club's academy teams or talking things through with his trusted cadre of lieutenants in his office. It is always relaxed: his gourd of mate - the bitter herbal tea Argentinians drink by the gallon - to hand, a little music on, an incense stick burning.
By 8 or 9pm, the security staff at Hotspur Lane have to take extreme measures to dislodge the 44-year-old. The best way to persuade him to leave, they have found, is just to turn the power off.
There are plenty of workaholics in football. Most managers will at least tell you that they are the first to arrive in the morning and always the last to leave at night. Even by those standards, though, Pochettino may well be an extreme case.
His friends and colleagues are quick to describe him as a devoted family man, spending whatever spare time he can with his wife, Karina, and his sons, Maurizio, a pacy right winger in Spurs' Under-15 team, and Sebastiano, studying sports science at Solent University in Southampton.
But Pochettino admits that he does not spend as much time there as he might. As he readily confesses, he does not really "have a life outside football".
He keeps himself fit in the gym at Spurs' training ground, he tries to return to Barcelona, where he retains a home, once every six weeks or so and, thanks in part to Karina's influence, has become an ardent devotee of eating organic food. He loves rugby and has even developed a rather unlikely interest in darts.
All of it, however, is secondary. His life is guided by one over-riding passion, one that borders on obsession. It is that work ethic which has allowed him to alter his club's DNA in the space of little more than 18 months, transforming Tottenham from also-rans into Premier League thoroughbreds, and in the process establish himself as a key figure in English football's new dawn.
Whatever Roy Hodgson's national team go on to achieve at Euro 2016 or at the 2018 World Cup, they will owe more than a little to Pochettino for creating an environment that allows Dele Alli, Eric Dier, Harry Kane and the rest to flourish.
His relentless drive fits nicely with the public perception of Pochettino. His training sessions are famously draining. Jack Cork, the Swansea midfielder who played under him at Southampton, suggested "it feels like you need two hearts" to play the high-tempo, high-risk pressing game he demands.
In pre-season last summer, on some days he had Tottenham's squad doing three two-hour stints every day. His approach, undeniably, echoes the coach who he admits "marked" him the most during his playing career.
The story of how he first encountered Marcelo Bielsa as a 14-year-old has a touch of the apocryphal about it: Bielsa, then a youth coach with Newell's Old Boys, arriving at the Pochettino family farm just outside Murphy, in Argentina's gaucho heartland, at 2am and knocking on the door; his parents inviting him and his partner, Jorge Griffa, in for a coffee; Bielsa asking if he could see Pochettino as he slept, looking at his legs and saying: "Look, Jorge, he has footballer's legs."
With Newell's, under Bielsa, Pochettino won the Argentinian title at age 19. For a few months in 1993, he shared a room with Diego Maradona, the player he admits was his idol. They made an unlikely pairing: the little wizard and a long-haired, tough-tackling central defender.
Pochettino was, in his own estimation, a "naughty" player; he is proud of it. "My first action in a game was always a yellow card," he said in February, a broad and satisfied grin on his face.
He would go on to leave Newell's for Europe, working with Bielsa again with Espanyol and the Argentina national team, as well as enjoying spells in France, with Paris Saint-Germain and Bordeaux.
He remains in contact with his mentor and he acknowledges that his footballing beliefs are laced with Bielsa's basic principles.
It would be unfair, however, to cast Pochettino as a mini-Marcelo. While the way he sees the game and the work he demands of his players may owe a little to Bielsa, his approach to management, the rapport he builds with his players, does not. The atmosphere that Pochettino creates - cordial, laid-back, collaborative, loyal - is a reflection of him, and him alone.
It is, those who know him and work with him say, the little things. Tottenham's players shake hands with everyone when they arrive in the morning: each other, the club's ancillary staff. He did not have to issue an edict to make them do so; he does not really do commands. Unlike many of his peers, he has not introduced rules about players eating together. He treats his charges as adults, trusting them to eat what they should, when they want.
Likewise, he does not believe in fines, or threats. He does not want his players to feel like they are at school. He would much rather make them see the training ground as home and their colleagues as part of their family.
He does not summon players for meetings: the door, instead, is always open, any of his squad welcome to come in for a coffee and a chat when they wish. He wins their loyalty not through authoritarianism but through a personal touch. At Southampton, he used to make a member of his squad a green smoothie - full of fruit and vegetables - for breakfast every morning.
Many of those ideas, he says, come from the master's degree in business development he studied after his playing career ended in 2006. Going to university allowed him to do that, and it gave him "ideas for how to run a club". All that is left to accomplish now are top honours as a manager.
THE TIMES, LONDON