TONIGHT BARCA PROVIDED the proof: never bet against this team. No matter the form, no matter the framework, never doubt their capacity to raise their game when it’s most required.

Underdogs? They dramatically overturned that tag.

Indeed, in a fair few ways, this was an even more impressive win than the fabled 5-0. Certainly in terms of character.

Because, make no mistake, Barca were under pressure. Not only did they have to win to pretty much keep the Spanish title race alive, they had to do so against a Real Madrid that have been in absolutely rampant form. Worse, they immediately went 1-0 down amid a performance that was atrociously error-strewn early on.

But they didn’t just overcome that start. They completely closed out the game in emphatic fashion. The manner in which Guardiola also reacted the game’s flow and made key alterations brought about an important tactical victory over Mourinho too.

Indeed, had Barca been more clinical, then the scoreline could have even been more embarrassing than the 5-0. In the last five minutes, they could have tacked on at least another four goals.

And, as fortuitous as Xavi’s key second goal might have been, it shouldn’t be forgotten that the equaliser – after what was a very difficult opening 20 minutes for Barca – came out of sheer excellence.

Alexis still had a lot to do and two defenders to beat when he received the ball at the edge of the box. But he finished superbly by drilling the ball into the bottom corner. Top-class.

Of course, the supreme Leo Messi assist was a perfect illustration of one of the deepest differences between the sides.

Moments before it, Cristiano Ronaldo had the opportunity to make it 2-0 by squaring to Angel Di Maria. Instead, he selfishly shot. It undeniably became a key moment.

And, while the two situations were different, it did encapsulate the same old story.

Messi is a team player who seamlessly fits into an organic team, enhancing it and completing it. Ronaldo, by contrast, is a pure individualist who is merely an extension of a supremely organised Real Madrid team. In that sense, they are a broken team. And the potential folly of basing your attacking around one player – no matter how devastating – was shown here.

Ultimately, Ronaldo could have made 2-0 and 2-2 at different points of the game. He missed. And, within moments of both, it was 1-1 and 1-3 instead. Despite his undeniably qualities, it won’t do his reputation as a temperamentally suspect player in the biggest games much good.

His sheer selfishness can be a liability in the biggest games, as we saw tonight.

Barca, on the other hand, once again illustrated what a transcendent, sublime team they are. At times in the second half, they toyed with Real. And, as if to underline their dominance, the clincher was a classically un-Barca goal: a deep cross and a header.

And, clearly, Barca remain at least a head above Real in terms of quality.

For the moment, that’s not the case in the league table. But the more significant impact of this result will be in the long-term. At the very least, Barca remain masters of their own destiny. Had they even drawn at the Bernabeu then – in the context of this division – they would have to beat Real at home and hope for a favour elsewhere. Instead, the initiative swung back their way.

Moreover, it’s entirely possible that Mourinho and Real will start to develop a damaging complex about Barca. So far, when it’s come to the games that actually matter, the Catalans have won them all. No matter what Mourinho has tried – from aggressively shutting up shop to relentlessly pressing as much as possible – it has all only had one outcome: Barca eventually reasserting their superiority.

Certainly, that was exactly what happened at the Bernabeu.