The city of Culiacán in north-west Mexico, best known as the bastion of the notorious Sinaloa cartel fronted by the billionaire drug kingpin Joaquín “El Chapo” Guzmán, was an unlikely place for Manchester City’s new manager, Pep Guardiola, to begin the process that would culminate in him becoming the world’s most sought-after coach.

Baseball, not football, has long been the most popular sport here and the newly founded local side Dorados de Sinaloa were minnows locked in a desperate relegation struggle when Guardiola, who turned 35 that month, arrived in January 2006.

It was hardly the typical destination for a veteran footballer looking for one last pay cheque but, having won more than a dozen trophies at Barcelona and made a fortune playing in the Qatar Stars League, the Olympic gold medallist and European Cup winner did not make the move in search of further financial reward or another trophy to add to his collection.

Instead it was here, under the tutelage of his old friend Juan Manuel Lillo, who had taken over at Dorados the previous summer, that Guardiola began to prepare for what has proved one of the most spectacular managerial careers in modern football history.

“We were in our second year in the top division and we’d just brought in Juan Manuel Lillo as our coach,” recalls the Dorados founder and former president, Juan Antonio García. “He told me there was a real possibility that we could sign Pep, who’d just reached the end of his contract in Qatar. Pep was already taking his coaching badges and the objective of playing in Mexico was above all to be close to Juan Manuel.”

The pair had first met in 1998, when Guardiola played for Barcelona in a 4-2 win over Lillo’s Real Oviedo. “At the end of the match he knocked on the changing room door and he told me: ‘I love your teams, I’ve heard great things about you, can we be friends?’” Lillo says. “How the hell could I not want to be friends with a player I admired as much as Guardiola?”

They stayed in close contact and when Lillo took charge of Dorados he found that Guardiola was easily persuaded to join him. Shielding the defence in Lillo’s favoured 3-4-3 formation, Guardiola scored once but suffered persistent injuries that restricted him to 10 league appearances. “He already had a coach’s mentality,” Lillo notes, and they would talk for hours after training each day about the importance of possession and different ways of reading the game.

Life at Dorados could scarcely have been more different from what Guardiola was accustomed to at Barcelona. The team trained at a local waterpark with only a palm-roofed gazebo for a changing room. The players could not even cool off after working up a sweat beneath the scorching morning sun because there were no showers and the waterpark was closed for the season.

Guardiola was on “by far the lowest wage he ever made,” García says, but Dorados were on the brink of bankruptcy and at one point they had to stop paying their players. “That had never happened to Pep before. We weren’t paying him or anyone so the players protested by not wearing the official club uniforms at training. Pep joined in out of solidarity for his team-mates.”

García adds that Guardiola was “a great professional who united the changing room. Even back then his vision as a leader was clear. He was a leader and a coach on the pitch, always organising the team. He was completely focused in preparing for the next phase of his career as a coach.”

Pep Guardiola was well schooled in possession-based play under Johan Cruyff, left, but his time in Mexico broadened his football education. Photograph: BPI/Rex/Shutterstock

While Guardiola had already been well schooled in possession-based play under Johan Cruyff, Dorados’ former assistant coach Raúl Caneda believes he and Lillo helped the Catalan to refine his understanding of collective positioning, defending from the front, and the idea that defence and attack are not separate entities.

“We tried to be a well organised and disciplined team that would keep the ball,” Caneda says. “We didn’t leave much down to improvisation, we wanted everyone to sing from the same sheet. We had a well defined style and we were very competitive despite being a humble team.”

Guardiola would always study Dorados’ next opponents closely and whenever he was absent through injury he would fidget beside Lillo on the bench and help to deliver instructions. “Many players today become coaches by virtue of their name but Pep knew this was not enough,” Caneda adds. “He was very intelligent, very humble and eager to learn, and he soon became a very complete coach with great knowledge of the game.”

A decade on from his six-month stint in Culiacán, Guardiola is remembered fondly by the few locals who knew him well. “Every fortnight he gave me envelopes full of cash to hand out to the lowest paid employees at the club,” says Eliseo Martínez, his former guide and chauffeur. “He used to give me 3,000 pesos a fortnight. That was a shitload of money 10 years ago, almost half my salary.”

Many remember the Catalan as a reserved character but Martínez recalls that he loved trying to master the colourful local slang. “He never got it quite right,” he says with a chuckle after imitating Guardiola’s vain attempt at pulling off a particularly obscene phrase.

Rarely recognised in public, Guardiola spent much of his time relaxing in his favourite restaurants and cafés. His photograph hangs proudly on the wall of La Cocinita del Medio, a small, unpretentious establishment where he stopped off after training most days for a lunch of prawns, stuffed peppers or enchiladas.

“He was well mannered and very generous,” says the owner, José Luis Bracamontes. “He’d often come in with his team-mates but he’d never let anyone else pay. Sometimes after eating he’d even take the dirty plates to the kitchen himself.”

Although Guardiola could not stomach the spicier Mexican dishes, Bracamontes felt he adapted well to life in a troubled city that the United States advises its citizens against visiting.

As the home of Mexico’s dominant Sinaloa Cartel, Culiacán has long been synonymous with narco culture. The infamous El Chapo, who was recaptured in January after twice breaking out of maximum-security prisons, owned at least seven houses there, all linked by a network of secret escape tunnels that ran into the city sewers. Guardiola arrived just as Culiacán was about to enter the most turbulent period in its history. Later that year the Mexican government would unleash the army on the nation’s cartels, initiating a savage war that would claim some 200,000 lives over the next decade.

Guardiola lived alone in a hotel at first, with his family later flying out to join him, but he never felt the need to request a security detail. “He was here at a difficult time,” says Bracamontes, whose home backs on to one of El Chapo’s now boarded-up safe-houses. “It was a very violent year for Culiacán, with shootouts in the streets, but he never talked about it and he didn’t seem worried by it.”

One of Guardiola’s closest friends in Mexico was Rodolfo Jiménez, the owner of Culiacán’s classy, dimly lit Café Miró, where the pair would swap books and bond over their mutual love of the Catalan musician Lluís Llach. Guardiola would later invite Jiménez and his family to stay at his New York apartment during his sabbatical in 2013.

“He’d often come on his own to read his books and have a beer or a glass of wine,” Jiménez recalls. “At this point he never imagined what was going to happen [in his managerial career]. He told me his dream was simply to coach young children at the Barcelona academy.”

Dorados ended that season in eighth place, their highest finish in the club’s short history. That would normally be enough to progress into the final knockout phase of the season but instead they were relegated under Mexico’s convoluted system for having the lowest points average over the past three years. It was an inauspicious way for Guardiola to end his illustrious playing career. “He suffered a lot as the prospect of relegation drew nearer,” Jiménez says. “Those were difficult days but he went from hell to glory because just three years later he won the Champions League.”

Pep Guardiola has every possible luxury available to him at Manchester City but at Dorados de Sinaloa life was very different. Photograph: Barrington Coombs/Getty Images

In late 2011, with three La Liga titles and two Champions Leagues under his belt and widely regarded the world’s most coveted coach, Guardiola would look back on his time in Mexico and describe Lillo as “an essential figure” in his development: “I think highly of him and I’m very grateful to him, because he was very generous and passed his knowledge on to me.”

Unfortunately for Lillo, his former apprentice’s competitive spirit would always take precedence over any such charitable sentiment on the pitch. They were reunited in Spain in November 2010, when Guardiola’s irrepressible Barcelona side humiliated Lillo’s Almería 8-0. Lillo was sacked hours later. Although prickly when reminded of the result, Lillo insists he does not hold a grudge. Aiding Guardiola’s development was “a very gratifying experience”, he mutters. “He’s like a son to me.”