Mauricio Pochettino was appointed as Tottenham manager to restore flair and a winning style. Chairman Daniel Levy looked to the Argentinian to get the best out of Spurs' expensive signings from the summer transfer window of 2013 and to avoid slipping further behind the Premier League's elite.
Despite his remit being to improve Tottenham's attack and excite the fans at White Hart Lane, his focus in the recent transfer window was the defence.
Spurs made six signings; four of those were defenders, an entire back line, and a new goalkeeper in Michel Vorm and a defensive midfielder were brought in as well.
If Pochettino is to implement his philosophy, he must build from the back in both literal and metaphorical terms. Evidently, having observed Spurs as Southampton boss and for a short period after moving to White Hart Lane, Pochettino identified the defence as the most clear weakness.
Having played as a central defender in Argentina, Spain and France, Pochettino built his career on his understanding of the game.
Pochettino learned to play under Marcelo Bielsa. A maverick coach, Bielsa believes in an aggressive, demanding style of defending. His whole team defends as a unit, and that Bielsa spirit was present in both Pochettino's Espanyol and Southampton teams.
Esquire produced a fine background piece on Pochettino's personal history and the origin of his defensive strategy.
Pochettino's footballing philosophy evolves from his back line. They set the pace in both attack and defence.
His defenders must be capable of pushing out aggressively and making the first pass from the back. When his teams win the ball, they look to quickly transition forward.
Then-Barcelona manager Pep Guardiola described Pochettino's Espanyol side as a team that "look for you" in defence. That aggression requires skill and supreme fitness.
"It does feel like you need two hearts to play that way," said Jack Cork of Southampton's defensive style under Pochettino, per the Esquire report.
"High-energy" and "high-tempo" are the key words used to describe Pochettino's Southampton. Last season they suffered occasional lapses when their fitness let them down. Pochettino now has the squad to avoid that pitfall. His style of football will exhaust his players but, unlike last season, he has vital strength in depth.
Pochettino clearly saw that Michael Dawson was incapable of this style of play. He has been sold to Hull City. He also was clearly dissatisfied with Danny Rose as the only senior left-back in his squad. Rose has admirably fought for his place so far this season, but he is now an option and not a default selection.
While Ben Davies has yet to make a Premier League start, his assured performances at Swansea won him his £10 million move to Tottenham. He was introduced from the bench against Liverpool to tighten the left flank after the Reds scored their third goal.
Pochettino now has two very different left-backs. Rose can provide the pace and flair in attack, while Davies is strong and solid in defence.
He has five central defenders that he can rely upon in his system. The arrivals of Eric Dier and Federico Fazio strengthen the squad depth while providing legitimate competition to Younes Kaboul and Jan Vertonghen. Vlad Chiriches has been criticised for his idiosyncratic style but he has the physical tools to contribute and, well coached, can help make Spurs better.
Pochettino can rotate when his players are fatigued and when certain oppositions demand it without sacrificing quality.
Fazio is yet to make his debut but brings experience and cultural familiarity with Pochettino. He is a more than able deputy for Kaboul. There is every chance that Fazio can oust the Frenchman as Vertonghen's starting partner. He has Kaboul's aerial prowess although he lacks the brute strength.
Kyle Walker's recent abdominal surgery means that Pochettino will not be able to rely on his first-choice right-back for some time. The signing of Eric Dier has already paid dividends. The young Englishman has impressed with his maturity and he has added some crucial goals.
After signing from Sporting Lisbon, Dier could have been forgiven for suspecting he wouldn't play often. He has already carved a place in the squad, but with Walker's uncertain recovery date, he is now a key member of the defence.
The January arrival of DeAndre Yedlin will provide further depth at right-back.
Tottenham's protracted pursuit of Morgan Schneiderlin ended in failure, but Benjamin Stambouli promises to be an able substitute. The former Montpellier midfielder is versatile and fills a crucial role in Pochettino's system.
Much like Schneiderlin, Stambouli screens the back line and plays the first pass out of defence. He is vital to both the pressing game and the rapid transitions that mark out Pochettino's teams.
As FourFourTwo pointed out in October 2013, Pochettino turned the leaky Southampton back line into a watertight defensive unit.
In his first season in charge at Espanyol in 2009-10, Pochettino built a resilient defence that finished better than Champions League qualifiers Sevilla.
Now, the new Tottenham boss has the chance to do the same at Spurs. Last season, Tottenham conceded 51 goals, only fewer than Newcastle and Stoke City of the top 11 teams.
If he can tighten Spurs' defence, Pochettino's philosophy will have its integral base. From there, he can build his attack and allow his clearly gifted squad to flourish.
Pochettino is armed with the crucial resources to build his defence. He has an excellent first-choice defence and strength in depth.