Mauricio Pochettino does not give much away at press conferences, but on Wednesday he revealed a side to his personality which had been largely private until then. Tottenham Hotspur’s head coach, outwardly affable and light-hearted, has a cold, ruthless edge which he made very clear as he castigated Andros Townsend in front of the cameras, throwing the winger’s Spurs career into serious doubt.

“Where there is an action, there is a consequence,” Pochettino said. “If you behave in the wrong way, you always need to pay. He needs to learn about football, about behaviour, about discipline, about a lot of things.”

Townsend was fined, banished from the main group, and suspended from selection after a public row with fitness coach Nathan Gardiner. He is unlikely to play for Tottenham again. “I am friendly,” Pochettino said, “but discipline is very important.”

The story of Pochettino’s 18 months at White Hart Lane has been of him moulding a young squad in his own image: competitive, hard-working and utterly committed to the cause. The team he fields at Arsenal on Sunday afternoon, hoping to climb into the Champions League places, will include no player about whom he has any doubts.

Pochettino inherited his squad from Tim Sherwood, who bemoaned a lack of “guts and character”. Pochettino’s solution has been to dispose of all the players he did not like, did not trust and would not come along with him.

By this time last year he had realised who those players were. Younès Kaboul , who was officially club captain, Étienne Capoue, Benoît Assou-Ekotto, Emmanuel Adebayor and Aaron Lennon barely played for him again. Adebayor and Lennon returned for pre-season training this summer, but were not given squad numbers or allowed to train with the main group. “I went back in for pre-season and there were a few of us told they were not going to be in Tottenham’s plans,” Lennon said. “It wasn’t just me, there was a complete overhaul.”

None of which means that Pochettino is vindictive or unpleasant. Rather, he knows what he wants from his players, which is total commitment to his philosophy, his way of training and playing. Anyone who strays from that is straight out.

It was the same at Southampton, where Pochettino spent £13m on Dani Osvaldo, his old striker from Espanyol. When Osvaldo headbutted Jose Fonte in training, Pochettino said he would never play for Saints again, and so it proved.

Those who know Pochettino do not say he is a fiery Argentine with a short temper, but quite the opposite. He is markedly calm and level-headed, whatever the result. At times, such as during a match, he can be tactile and encouraging, but his natural mode is cold authority. Jesus Perez, his assistant, does more of the personal interaction.

Although the door to Pochettino’s office at the training ground is nominally open, players who come to him to ask why they are not playing get a curt response. Pochettino has his own explanation, about what it is to be a professional footballer, and why there is no use moaning to him.

“When you sign a contract as a player, you need to understand that you don’t sign to play, you sign to train,” he has said. “Then you wait for the decision of the manager to pick the players. This is football.”

It is an uncompromising attitude, but one that has served Pochettino well so far. It is an attitude he picked up from the most important person in his career to date, legendary coach Marcelo Bielsa, who managed him at Newell’s Old Boys, Espanyol and the Argentina national team, and whom Pochettino calls his “father” in football.

Oscar Garcia, recent manager of Brighton and Watford, played with Pochettino at Espanyol and recognises the similarities between his approach and Bielsa’s.

“I know Pochettino’s mentality, similar to the Bielsa mentality,” Garcia told The Independent. “I know a lot of players who played for Bielsa at Athletic Bilbao. Bielsa only has one way. If you don’t want to go this way, you will not play at all.

“When I played with Pochettino for Espanyol, he had a strong mentality, he was a leader of the team, and of the young players. He organised the team defensively. He had a typical Argentinian mentality, very competitive. He wanted to win every game and every training session. All the players who played under Bielsa learned a lot from him, and tried to copy Bielsa.”

Premier League Power Rankings: Week 12 Show all 17 1 /17 Premier League Power Rankings: Week 12 Premier League Power Rankings: Week 12 <b>17) Andre Ayew (Swansea City) - down 2</b> After a blistering start to the season Ayew, like Swansea, had cooled off before the recent trip to Villa Park where against the relegation candidates he found his best form and eventually added the crucial match-winner. Things were much tougher against Arsenal last time out but this weekend Swansea will be eyeing maximum points again. If they're to get them, Ayew will be crucial. Last Fixture: L - 0-3 - Arsenal Next Fixture: Norwich (a) 2015 Getty Images Premier League Power Rankings: Week 12 <b>16) Joleon Lescott (Aston Villa) - up 1</b> Remi Garde takes charge of his first game as Aston Villa manager this weekend and having watched his new side in person on Monday night, he'll have a better idea of the task ahead. 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Pochettino likes to say his tactical philosophy is different from Bielsa’s but the influence is clear. Arsenal captain Mikel Arteta played with Pochettino at Paris Saint-Germain and said last year that Bielsa was “his hero and his mentor”: “Most of the concepts Pochettino has tried to put into his teams are from Bielsa.”

What Pochettino also learned, growing up with that famous Newell’s team, was the special power and meaning of a derby. Newell’s great rival is Rosario Central and even now, Pochettino still thinks in those terms. In March, before Spurs played Manchester United, he was asked about Angel di Maria. “He is the opposite of me,” Pochettino joked. “I am leproso [Newell’s], he is canalla [Central].”

Through his whole career, Pochettino has fed off the passion and energy of derbies, from Newell’s v Rosario Central, to Espanyol v Barcelona, and now Spurs v Arsenal, the latest instalment of which takes place at the Emirates.

Pochettino was the first Espanyol coach to win at the Nou Camp in 27 years, overturning Pep Guardiola’s great team in February 2009. The greatest moment of his Tottenham tenure to date, even better than routing Chelsea and Manchester City at home, was the epic 2-1 defeat of Arsenal at White Hart Lane in February, when Spurs overwhelmed their greatest rivals with their commitment, intensity and emotional energy, climaxing in Harry Kane’s header four minutes from the end.

Those are the qualities that Pochettino demands from his sides and from his players. “We need to be ready,” he said late on Thursday night. “We need to be strong in our minds, and try to win the game, because we know what the derby means.”