Zidane took over from Rafa Benitez in January after Madrid had drawn 2-2 at Valencia. Real were only two points off the pace after that, but it was effectively five because Barcelona had a game in hand. And under the Spanish coach, it certainly did not seem as if they would be competing for a major trophy at the end of the season.
However, heading into his team's final fixtures of the campaign, Zidane is in contention for two: La Liga and the Champions League. And while his side have benefitted from a favourable draw in Europe, the turnaround has been dramatic.
In the Primera Division, Zidane has led Real to 16 wins out of 19. In exactly half a season in charge, he has won 50 points from a possible 57 which, projected over an entire campaign, would mean 100 - the record total held by Jose Mourinho's Madrid in 2011-12 and Tito Vilanova's Barca in 2012-13.
Zidane has beaten everyone, Barcelona included, except for three teams: Betis, Malaga and Atletico. Real drew 1-1 away to the two Andalusian outfits and lost 1-0 at home to Diego Simeone's side, their rival in the final of the Champions League in Milan on May 28.
In doing so, Zidane's side have hit 61 goals and conceded only 16 in their 19 Primera Division matches.
That is an exceptional return and one that has seen Real return to the reckoning in the title race. With one round of La Liga left, Zidane's side sit one point behind Barcelona and if Luis Enrique's men slip up away to Granada on Saturday, they are in place to produce what just a few weeks ago would have seemed an unbelievable upset.
Madrid are away at Deportivo La Coruna on Saturday in a game they will be expected to win, but Barca - despite losing 1-0 at Granada in 2013-14 - remain big favourites to win at Los Carmenes and claim what would be a remarkable sixth title in eight seasons.
Just a few weeks ago, La Liga looked like a one-horse race. Ahead of the Clasico at Camp Nou on April 2, Barca led Real by 10 points and Atletico by nine. But after losing that one and then their subsequent defeats against Real Sociedad and Valencia, Luis Enrique's side have allowed their fierce rivals back into the fight for La Liga.
"I'm happy with the work we are doing," Zidane said last weekend. "But it's the players who have gifted us everything. Above all, I'm happy with the players, with my staff and with the fans."
And those fans will be happy too because Madrid's season looked likely to implode in the winter. Instead, however, Real are in contention for the two trophies that matter most - and that was precisely the objective at the beginning of the season.
So even if Madrid end up second in La Liga this time around, Zidane's points ratio represents a big positive looking ahead to next season. It may be too late for his team to win La Liga in 2015-16, but Real's renaissance means the Primera Division is set for a fantastic finale on Saturday and if they can maintain this form going into the coming campaign, it will be even more exciting than this in 2016-17.