Zinedine Zidane and Ernesto Valverde made their concession to festive gluttony by bringing along more central midfielders than anyone could feasibly need for El Clasico.

That Barcelona eventually gorged upon a 3-0 win could have wide-reaching ramifications for the Real Madrid boss.

Count Sergi Roberto, playing in his less-favoured right-back role for Barca, and there were nine midfielders on show at the Santiago Bernabeu.

It made for an absorbing, clattering and crescendoing first half, where the likes of Luka Modric, Toni Kroos and Andres Iniesta were made to furrow sweat-flecked brows and search that little bit harder for the playmaking space they crave.

Madrid duo Modric and Kroos did so to fine effect in the hosts' better moments, attacking Barca precisely from the inside left and right positions, while Iniesta glided around imperiously – the silk in a match at times as abrasive as sandpaper.

Decades of fierce rivalry between Barcelona and Madrid are currently embellished by a fractured political climate, but Iniesta's status as a national hero rises above the fray.

Barca's 33-year-old captain was applauded by the home fans when he returned to the field following a painful coming together with Dani Carvajal. Scoring Spain's winner in a World Cup final remains strong currency.

All the visitors' most enterprising play before Luis Suarez's game-breaking 54th-minute opener had Iniesta and Lionel Messi's creative telepathy at source, even if the latter's work was complicated by El Clasico's new specialist.

Mateo Kovacic last started domestically in the Supercopa de Espana back in August, when he man-marked Messi. In Zidane's eyes, the Croatia midfielder is akin to the intrepid secret agent from your favourite action movie. A horrible task that nobody wants to tackle… and here comes our hero from the wilderness to get the job done by any means necessary.

Initially, there was a little more to Kovacic's role. He acted as Madrid's midfield wildcard – harassing Messi as soon as Barca ventured forward, but making life equally uncomfortable for Sergio Busquets when Zidane's men were on the front foot.

It meant Barcelona's famed build-up play rarely got off the ground for the first half hour, when they were grateful for Paulinho's bustling presence.

In a move far removed from the tiki-taka playbook, goalkeeper Marc-Andre ter Stegen regularly pumped long balls towards the Brazilian, stationed to the right of a midfield quartet.

Not for the first time this season, Paulinho – a man who has delighted in silencing critics who ridiculed his August recruitment from Guangzhou Evergrande – was Barcelona's most visible goal threat. He stretched to fire goalwards from a majestic Messi pass in the 30th minute, only to be denied by a world-class save from Keylor Navas.

The Costa Rica keeper also kept out a Paulinho header before the break, but there was a familiarly Barca look about the opening goal.

The midfield arm wrestle had twisted in the direction of Valverde's men, Madrid's mental and physical exertions taking a toll. Kovacic found himself almost exclusively on Messi detail early in the second period.

Having been virtually suffocated earlier, Busquets breathed in the crisp winter air and strangled Madrid's title defence as he shimmied elegantly, surveyed his kingdom in front of the back four and released Ivan Rakitic.

As the surge progressed, Kovacic continued to glance evermore anxiously towards Messi, his fear of the great man persuading him against the obvious course of action that was to confront his marauding compatriot.

Rakitic charged through a central area suddenly and impossibly vacant, found Roberto haring down the left and the full-back's delivery was one even an out-of-sort Suarez could not fail to dispatch.

Carvajal's Lev Yashin impression brought a red card and a penalty at the end of a Barca counter-attack that began with Casemiro's reliable passing going south. Messi's converted spot-kick means Zidane's game plan had emphatically gone in the same direction.

Substitute Aleix Vidal piled on extra punishment against the run of play in stoppage time after the depleted Madrid rallied bravely.

Ludicrous as it sounds for a two-time European and world-champion coach, this result could have grave consequences for Zidane's long-term job prospects.

Yes, his Kovacic plan worked perfectly for 45 minutes, but he ultimately picked an extra defensive midfielder and left Isco, Marco Asensio and Gareth Bale on the bench for a game that ended with Madrid 14 points off the pace in the title race.

Victory in the last-16 of the Champions League against a swashbuckling Paris Saint-Germain is now a must for Zidane. The former Galactico is explicitly aware of the terms of employment at the Bernabeu and Saturday's failure will be viewed dimly.