Mariano Rajoy hasn't even set foot inside Moncloa and already something is changing. This is a new era; power has changed hands – in parliament and on the pitch. That, at least, is the theory. They say you shouldn't mix football and politics but in Spain it often seems impossible to do anything else. You can try to take the football out of politics but you can't take the politics out of football. The search for political explanation for sporting success and failure, for footballing meaning, is constant. When it comes to the battle that really matters, Madrid versus Barcelona, it is unavoidable.

On Sunday 20 November, the Partido Popular won general elections, returning to power for the first time since 2004. Out went the PSOE and its Barcelona-supporting leader, José Luis Rodríguez Zapatero; two defeats later, in came Mariano Rajoy. "Real Madrid get strengthened," ran the cover of the freebie Catalan sports newspaper El 9, alongside a rather odd picture of the victorious candidate jumping for joy. "Rajoy, a self-confessed Madridista, brings the PP to government," continued the cover: "a party with which [the Madrid president] Florentino Pérez and the white team have always enjoyed a magnificent and fruitful relationship."

And so it was that as they gathered to celebrate with the world's worst disco down at PP HQ on calle Génova, power shifted from FC Barcelona to Real Madrid. Zapatero has gone. So, after this Saturday's 1-0 defeat at Getafe left them six points behind Real Madrid at the top of the table, have Barcelona's title hopes? "Barça are six points away!" cheered AS's cover on Sunday. This morning, they lead on the betting odds: for the first time in three years, Madrid are favourites. Even El País noted: "The league escapes Barcelona." And, never mind the football or the fact that Rajoy's not had the chance to do anything yet – Ana Pastor, the woman the right most loves to hate, and first in line when the cuts come, was still on TVE this morning – it's all down to the change at the top.

You'd think so anyway. El 9 weren't the only ones drawing the parallel – on both sides of the divide. Much of it was tongue in cheek. And much of it, going back a century, is rubbish. During Spain's Second Republic Real Madrid won two titles, both of them before the right won the 1933 elections; Barça won none. During the harshest years of the dictatorship, from 1939 to 1953 – when Spain's tentative opening up began, not least with the arrival of Alfredo Di Stéfano (and that's a whole new issue, as is the civil war itself) – Madrid didn't win a single league title; Barça won five. And after Franco's death, it took Barcelona 10 years to win the title and six more to win another one; Madrid won the league in 1976, 78, 79 and 1980.

But, still. In March 2004, Madrid were on course to win a treble. At least if you believed the Madrid press – and you really shouldn't – they were. Then the Atocha train bombings happened, the PP lost the elections, and things started to go wrong for Madrid. Their collapse came; Valencia beat them, Barcelona overhauled them and then Barça took over. Under the PSOE, Madrid won two titles – and because they came under the wrong club president, you'd think they hadn't even won those – while Barcelona won five.

Some people who should have known better, to their eternal shame, seriously tried to use the Atocha bombings as the reason, as if Madrid were somehow perfect until then – and not the dysfunctional club they actually were – and as if Barcelona were somehow complicit in the deaths. In fact, it was Madrid who were complicit in their own demise and the shift was already coming.

Just as this one might have been – if indeed it is a shift at all. Less than a week after the right's win, already the impact was being felt. Political parallels were being drawn everywhere. "The new president is called Real Madrid," wrote Di Stéfano in his weekly column, while El Mundo Deportivo's cartoon features a decrepit figure, symbolising the right and noting that there was a "simple explanation: the PP won and Madrid start winning, the way God wishes it."

That was one explanation. Luck was another. And another was that there is no shift: after all, it is only six points and it is only November.

On Saturday, Barcelona were defeated 1-0 by Getafe despite having well over 70% of the possession and taking 21 shots to Getafe's seven, seven to one on target. Getafe's goal had come from a corner and in the final minute Leo Messi had one ruled out for offside and another shot come back off the post – one of eight shots to do so this season. It was the first time Barcelona had been beaten in any competition this season – their unbeaten run goes back 27 games to April. It also was the first time they had failed to score away from home in an astonishing 43 games.

"Some people are setting off fireworks already," Dani Alves said. "They'd hand the title out to Madrid right now; happily, it doesn't get handed out for ages yet." "The league's not over," added Pep Guardiola, "and we'll get up again." As for Real Madrid's Alvaro Arbeloa, he was taking a little advice from Mr Wolf. Writing on Twitter, he warned: "Don't talk about how bad the bridge is until you've crossed the river."

True. But six points is a big gap and fortune alone does not explain the shift. This morning's Catalan papers insisted on Barcelona's ability to turn it round; The Dream Team, they noted, had done just that. Yet that was a different era. Under Pep Guardiola, Barcelona have never trailed Madrid by more than two points. And six points in a league where the title-winning total is likely to be over 90 – Madrid have failed to win either of the last two titles with 92 and 96 points respectively – is significant. Even a small slip is a big one now as the margins get finer and finer. Last season, Barcelona dropped only 18 points all season (four of those after clinching the title); they have already dropped 11 this time round. Madrid dropped only 22. The year that the Dream Team took the title off Madrid on the final day, their rivals had won just once away in the whole of the second half of the campaign.

Victory in the clásico would bring the gap down to three points; defeat would make Real Madrid's lead nine points – and that really would be a colossal gap. For Barcelona, winning the clásico is not an opportunity but an obligation; "our margin of error has gone," Alves said. This year, the first clásico is at the Bernabéu, not Camp Nou and before losing to Getafe this weekend, Barcelona have already drawn away with Athletic Bilbao and Real Sociedad. Their only away wins have been in Gijón and Granada – and both of those were 1-0. Puyol was absent on Saturday – just as he had been in each of Barcelona's previous seven defeats; without him, there is a lack of aggression and concentration slips too.

Barcelona are not playing as they once did. Their possession is going up – it averages 72.44% this season compared to 69% and 68% in the previous two – but the number of shots is down slightly. The shots they are getting are less clear, too. That was already happening to some extent last year – the Copa del Rey final, with Messi dropping ever deeper, was an example – but now it is more concerning for the Catalans. Messi is so brilliant as to disguise certain problems but they are there. Building to Messi is one of the factors that has narrowed Barcelona, creating a jam, and few players go outside as Thierry Henry once did – the absence of Pedro, through injury, has been significant, while the introduction of Isaac Cuenca could be an important variation, as could the return to fitness of Alexis Sánchez. As yet, though, there has been little impact away from home.

Talk of a plan B is a red herring but Barça do lack a certain variety – especially without Andrés Iniesta. What variety there has been is potentially problematic. There have been 13 different lineups in 13 league games and they look vulnerable from set-plays: "We are," Alves admitted, "a bunch of dwarfs and we need to improve." Guardiola has talked about using three at the back in order to attack more and be attacked less but the system does not always convince. Barcelona could hardly have attacked more or been attacked less before. They have played with a No9, a false No9 and two false No9s. Guardiola's desire to reinvent has not always proven successful. So far.

For Barcelona's approach to work, it needs pace, intensity and aggression. And identity. Right now, Barcelona do not have that. In August Guardiola recalled the days when the summer was spent on a pre-season not a tour and Barcelona look sluggish; on Saturday, he admitted they were tired as they came off the back of their Champions League game with Milan. After three successive years of international summers, this year there was a break at last but the season began with the European Super Cup and a Spanish Super Cup for which they had barely prepared. The World Club Championships is still to come – forcing Barcelona to crowbar in an extra game before the clásico. The ball is travelling slower and there have been 17 injuries.

The fatigue is mental as well as physical. One of the things that people overlooked when Barcelona won last year's league title and Champions League was just how emotionally tough they had proven. This season they will have to be even tougher; in most leagues and against most rivals you can drop points. In most leagues and against most rivals, just one defeat in 13 would be a wonderful start. But this is not most leagues and that is not most rivals. Standing before Barcelona are a Real Madrid team with astonishing variety in their play, strength in depth, talent, temperament, aggression, speed, power, precision, more control than ever before and a six-point lead.

Oh, and an ally in power.

Talking points

• At the end of the Madrid derby, Real's ultras held up a mock advert: "Worthy rival wanted for decent derby." Which kind of said it all. It's 12 years now since Atlético beat their neighbours. And once they were down to 10 men there was little chance of them breaking the run. It was a pity because until then it looked like a decent game but somehow you always know that they'll find a way. Manzano was furious with the ref afterwards; Mourinho, with a certain degree of irony, was furious with Manzano for sending his players out to kick and, as he shouted from the bench, playing something that "was not football". "Those carbon-fibre shinpads are expensive," he said but they're worth it." Match report here.

• Xabi Alonso put it best: "Iñigo Martínez is my idol." He scored an injury-time winner to give Real Sociedad a 3-2 victory over Betis. From inside his own half. It was the second time he has done so this season. The only question now is which of his two strikes is the goal of the season. View them for yourself here.

• Rayo Vallecano's fans held up banners complaining about the LFP after the league's decision to change the date and time of their game with Barcelona – three times. Not that it is just Rayo's fans who should be moaning about the LFP's rank incompetence and total disregard for them. It is every single fan in Spain.

Results: Rayo Vallecano 1-0 Valencia, Real Madrid 4-1 Atlético, Getafe 1-0 Barcelona, Betis 2-3 Real Sociedad, Levante 4-0 Sporting, Mallorca 2-1 Racing, Espanyol 1-2 Osasuna, Athletic Bilbao 0-1 Granada, Zaragoza 0-1 Sevilla, Málaga-Villarreal (Monday night).