His managerial CV was meagre. He had sat in the Real Madrid dugout alongside Carlo Ancelotti for a season as one of his assistants with little of note to do. He'd left no mark as boss of Castilla, Real Madrid's B team, failing to gain promotion from Spanish football's third tier during the 2014-15 season.
Then, after a jittery start—which included a 1-0 defeat to Atletico Madrid in February 2016—his Real Madrid team caught fire. He delivered a coveted 11th Champions League title. He racked up a Spanish-record 40-game unbeaten run and is on the verge of securing Real Madrid a first league title since 2011-12, as well as becoming the first manager to win back-to-back Champions Leagues in the competition's current guise.
Was there anything to suggest Zidane, one of the great footballers, would possibly become a great manager? Is he a good manager or a lucky one?
"What makes a good coach or a bad coach is baffling and mysterious," according to John Carlin, author of White Angels: Beckham, Real Madrid and the New Football and a columnist with El Pais. "It's part of the charm of football. The fan generally chooses to attribute magic powers to [managers], as if they were alchemists who can transform base matter into gold. The whole thing is continually surprising. We make our judgements after the event. Beforehand, we cannot predict a damn thing.
"The case of Zidane is particularly instructive. Anyone who employs their reason and saw the facts on the table would not have anticipated that he would be a successful coach. The experience he had was nondescript. Had his name not been Zinedine Zidane, there is no way Real Madrid—or any other Spanish first-division team—would have hired him to be first-team coach. He got there on basis of his name, because of his magnificent career as a player.
"He is testament to the enigma of the coach. He's been unbelievably successful [as manager of Real Madrid], and yet if you were to ask me would he be successful if, say, next season he went to Tottenham Hotspur or Chelsea or Manchester United, my instinct would be to say, 'No. He'd be a failure there.' But who knows?"
Paco Pavon, who lent his name to the expression "Zidanes y Pavones" while playing alongside him during the French star's five seasons as a Real Madrid player, says Zidane's collegiate nature has stood out to him. "When he was a player, his way of relating to his team-mates was always very good, and I believe that now as a trainer, this has helped him greatly."
Pavon cites the moment that Zidane took over from Benitez as being a critical juncture. The Frenchman's cop-on was exactly what the squad required. Benitez, with his overbearing tactics, hadn't jelled with all of his players. "Zidane entered the dressing room with a complicated situation," Pavon said. "He brought calm and common sense."
Carlin also singles out Zidane's Zen. "He conveys an attitude of serenity," he said. "He's the complete opposite of Jose Mourinho, for example, who was excitable—who sought scapegoats among referees [while manager of Real Madrid]. Zidane projects an image of great equilibrium. He's always immensely relaxed, somehow above the hurly-burly and nonsense of football."
Zidane also had instant street cred. For a decade, the replay of his stunning winning goal in the 2002 Champions League final against Bayer Leverkusen has been a closing scene for the montage of Real Madrid's glorious goals that play on the big screen before home games at the Santiago Bernabeu.
"Real Madrid is a unique team; there are stars in every position," Carlin said. "What one can argue is that if there are players who are absolutely brilliant in every position, the most important thing is to maintain a good collective psycho balance, to be successful at blending team spirit and soothing egos of the various players, making out of those ingredients a delicious dish.
"That's what Zidane has done well—he's got great calmness. He comes with a huge advantage at Real Madrid—he's one of the few people to come before that galaxy of great players with instant, total cred because of his name."
Perhaps Zidane's most notable feat as Real Madrid coach has been his ability to keep a squad full of egos on an even keel. He has rotated heavily, effectively playing a B team on the road for easier league ties. On Saturday, for example, only Sergio Ramos and Casemiro from his regular first-choice XI started the 4-0 win against Granada. "The key to the success of Zizou has been his magnificent management of the squad, his ability to convince players," Pavon said.
Zidane has persuaded Cristiano Ronaldo to see the virtues of respite. He wants him singing in the critical April-May months. For several years, an ageing Ronaldo has flagged when it came to the business end of the season, being notably unfit for the Champions League finals in 2014 and 2016.
Last season, he played every minute of every league game until the 34th game of the season, as per Diario AS, more than any other player in the league. Only he was knackered when it came to the Champions League final against Atletico in Milan.
Since March, however, Ronaldo has sat out league games against Leganes, Sporting Gijon, Deportivo La Coruna and Granada. In the big games, he has been fresh. In the quarter-finals and semi-final first leg of the Champions League, he has been a match-winner, banging in eight goals against two of Europe's strongest teams: Bayern Munich and Atletico.
Life has looked fortunately on Zidane. He had a gilded career as a player. He's been a lucky manager—Real Madrid's win in the 2016 Champions League was the only time a victorious team never encountered a previous winner of the tournament or league champions en route to the trophy.
Zidane was lucky with the two red cards doled out against Bayern Munich in this season's quarter-final; both proved decisive. He was lucky to meet a diminished Atletico side in the semi-final—older and more jaded in key positions than the side that won La Liga in 2014. He has been lucky with Gareth Bale's injuries this season—the Welshman's absence allows him to pick a more balanced side, with his replacement, Isco, scoring the vital away goal against Atletico in second leg of the Champions League semi-final.
Diego Torres, a journalist with El Pais and author of The Special One: The Dark Side of Jose Mourinho, says Zidane's luck isn't random. It's a function of his nature. "Zidane is a man with luck," he said. "But he is a man with courage and charisma, which are important virtues that help him to have good luck."
Zidane used his charm, for instance, to persuade Ronaldo about the benefits of game management and rest. He used his courage to make Casemiro a nailed-on starter when previous Real Madrid managers have bowed to pressure from club president Florentino Perez to jam the team with his attacking, Galactico signings at the expense of pragmatism. The Frenchman has bucked this trend. He wants a shield for his team—in the same way Claude Makelele provided ballast for the great Real Madrid and France teams Zidane played on—so Casemiro plays, relentlessly snuffing out opposition attacks in the middle third of the pitch.
The Real Madrid manager is a reluctant leader. It can be seen in his press conferences. He's stiff. He doesn't love the camera the way predecessors like Mourinho or Bernd Schuster do. He doesn't have the easy manner of Ancelotti. Torres questions whether Zidane even likes being a club coach.
"He does not like being coach because he does not have a vocation to be a manager of a club," Torres said. "His vocation is to be coach of a national team, possibly for France. He does not like being manager because he doesn't feel entirely comfortable being in charge."
Zidane knows he serves at the whim of Perez, a man who sacked the popular Ancelotti (Zidane's mentor) and Vicente del Bosque (who managed him while he was a player) immediately after winning a league title. The 44-year-old's relationship with Perez "is not especially good," Torres notes. It's cordial, professional.
"Florentino would like a more scientific trainer, more of a tactician—a trainer who is more like Mourinho, a trainer who is more sophisticated and not so simple" Torres adds, "Zidane knows his time as a trainer won't last too long."
Will it last much longer at Real Madrid? Zidane is holding a strong hand. He has such prestige among Madridistas, but his luck could change.
"Florentino Perez is absolutely ruthless in the pursuit of success and ruthless in his punishment of failure," Carlin said. "Should it happen that there is a surprise and Real Madrid win neither the Champions League nor the Spanish league, then all the credibility that Zidane has acquired is not going to count for very much."
Zidane has made his own luck; he will need fortune to be on his side if he is to remain at Real Madrid for the long term and become a managerial great.
Follow Richard on Twitter: @Richard_Fitz
All quotes and information obtained firsthand unless otherwise indicated.