Decisive days in La Liga

League titles are not decided in October. That has been the message from both Barcelona and Real Madrid players as Sunday's Clasico clash at Camp Nou draws closer. But a win for the Catalans will see them open up a seemingly unassailable 11-point lead over their title rivals. Round seven of La Liga, then, could prove decisive.

Barca have won all six of their fixtures so far in the Primera Division and a win on Sunday will make the Catalans huge favourites to reclaim the League title they lost to Madrid last term. Tito Vilanova hoped to hit the ground running after taking over from Pep Guardiola in the summer and, despite losing the Spanish Supercopa, his side have done just that. Now, they have a chance to take what could be a significant step towards the title. Already.

Currently eight points ahead of Real, a draw would suit the Catalans, but victory on Sunday would represent a real boost for Barca – and a big blow to Madrid's aspirations of retaining the crown the claimed in 2011-12.

Madrid cannot afford to lose on Sunday and are buoyed by the goalscoring form of Cristiano Ronaldo coming into this famous fixture. The Portuguese has hit six goals in his last two matches and has also netted in his last four appearances at Camp Nou, including the winner in last season's 2-1 success. That game all but decided La Liga – and this one may do, too.

Ronaldo recently reminded Barca that Madrid had beaten them before at Camp Nou, having overcome that particular psychological barrier in April. And Jose Mourinho's men also came out on top in the sides' last meeting, a 2-1 win at the Santiago Bernabeu.

That success handed Madrid the Spanish Supercopa but in the first leg at Camp Nou, Barca won 3-2 in a scoreline which flattered the visitors – Lionel Messi had been a whisker away from making it 4-1 before Victor Valdes' shocking error gifted Angel Di Maria a late goal which ultimately proved crucial.

In the end, the win for Barca felt hollow, almost like a defeat, as fans left the stadium depressed instead of delirious. After the game, Javier Mascherano summed up the mood when he said: "Don't forget that we actually won the match." Many had done.

Barca subsequently succumbed in the second leg as Pique and Mascherano were exposed at the Bernabeu. Home advantage will mean Barca's defence are likely to be tested less than on that evening, when Madrid missed a number of chances, but Mourinho will fancy his side's chances if the Argentine is paired at the back with Alex Song. And with Pique still struggling, that's more than likely.

Whatever happens, the result is likely to have a huge bearing on this season's title and at around 21:30 local time on Sunday night, either Vilanova or Mourinho will be under huge pressure. Cut the deficit back to five with a morale-boosting win at Camp Nou and La Liga is back on for Madrid. Lose and they will struggle to recover from 11 points adrift. It may be only October, but Sunday's game already looks decisive.

And it's not the only one. Atletico Madrid meet Malaga in a game which pits second against third. Atletico extended their impressive run of European victories with an albeit unconvincing win over Viktoria Plzen on Thursday, proving they can produce the goods even without playing well.  In La Liga, Diego Simeone's side have claimed 16 points from a possible 18 and if Real beat Barca on Sunday, they can go top with victory over Malaga later that night.

But beating Malaga is easier said than done. The Andalusians have made a superb start to their first-ever Champions League campaign, winning both of their opening matches convincingly to top Group C, and sit just two points behind Atletico in La Liga, with four victories and two draws in their six games. Ten games into their season, Manuel Pellegrini's men remain unbeaten.

With Barcelona and Madrid as strong as ever and Atletico and Malaga in fine form, Valencia are in danger of losing their top-four status this term. The Mestalla outfit have finished third in each of the last three seasons, but are starting slowly under new Coach Mauricio Pellegrino, albeit following a series of difficult fixtures at the beginning of the current campaign – they have already travelled to both Barcelona and Madrid.

This weekend, Valencia – in 10th place with just eight points – travel to local rivals Levante for the city's derby clash – and it is a game they will need to win in order to keep in touch with the likes of Atletico and Malaga.

Another fascinating fixture sees Athletic Bilbao host northern rivals Osasuna. And following their poor start to the season plus reports of player unrest at San Mames, only a victory will do for under-fire boss Marcelo Bielsa, whose promising project now appears to be falling apart. Indeed, defeat could even spell the end for the troubled Argentine.

This weekend, then, could prove to be a decisive date for many in La Liga.