The past week showed everyone that Real Madrid are vulnerable. Everyone it seems, except Ronald Koeman.

Consecutive defeats and some rather loud questions about the future of Zinedine Zidane meant Saturday's game at Camp Nou was one he dare not lose. For Koeman, this was a chance to go for the jugular, to show LaLiga and the watching world what improvements he has made to Barcelona since taking over in August.

Instead, the first Clasico of the season was a commanding 3-1 win for Madrid, a bruising outing for Lionel Messi and a 90-minute showcase of how unclear the Koeman blueprint seems to be.

He went, as expected, with Barca's first starting 4-2-3-1 in a Clasico since at least 2005-06, but his line-up was still puzzling. Ansu Fati is a rare talent with a robustness under pressure to match – and, of course, he scored here to cancel out Federico Valverde's opener – but Pedri, another 17-year-old, was chosen ahead of Antoine Griezmann and Ousmane Dembele as two of Barca's most expensive signings again began on the bench.

The two France forwards are hardly untouchables in this side, but starting a player of such limited experience as Pedri was a gamble that didn't pay off. He completed 79.5 per cent of his passes, the lowest rate of any starting player for Barca, and failed to have a shot or create a chance. It was a surprise that it took until the 81st minute for Koeman to bring him off.

By the time Griezmann and Dembele were summoned in the second half, with Barca chasing the game, it was too little, too late. Sergio Ramos, the major-general of Zidane's fiercest battles, had seen to that.

The Madrid captain can claim to be the most critical asset to either side of this famous rivalry, Messi included. Zidane had insisted this week he would not use Ramos were he not 100 per cent fit, but it sounded a hollow threat. Those chastening defeats to Cadiz and Shakhtar Donetsk had shown the boss that playing Ramos here was worth the risk.

So it proved. Ramos made four clearances, three interceptions and one crucial block from a Philippe Coutinho effort at 2-1. He misplaced just three of 55 passes and completed all 15 of those attempted in the Barca half. When Clement Lenglet foolishly took a handful of his shirt to concede a penalty, there seemed only one outcome. Not even VAR delays can throw Ramos off his stride.

He capped his display by stopping a late Messi run with an almost impudent back-foot challenge, the kind that will likely have fan accounts on social media sharing the footage every week until the reverse fixture.

Still, even with their captain back in the team, this is a flawed and fragile Madrid, with no fit recognised right-backs and who had only scored six goals in five league games, yet Koeman's set-up left them an easy ride.

After Messi had a shot well blocked by Thibaut Courtois 24 minutes in, Barca did not muster a single effort on target, meaning Luka Modric's composed late finish was scarcely even necessary. It was all too deep, too central and too slow; for Ramos and his fellow defenders, it was a picnic.

It is still early in the season to write off Koeman's chances, but two wins from five games and a six-point gap to Madrid at the top – albeit with a game in hand – are sufficient warning signs of the task at hand.

Ernesto Valverde's Barca were too rigid and Quique Setien's frighteningly open, but, after more than two months, we're no closer to knowing what kind of team Koeman's are.