The footballing world will immobilise on Sunday to witness what many protagonists have labelled 'the greatest match on Earth'. It's Messi vs Ronaldo. First vs second. Barcelona vs Real Madrid.

The season's second El Clasico is pivotal, and with a solitary point separating the sides at the summit of La Liga, the outcome of the Nou Camp clash could prove critical in the title race by the season's end.

Barcelona currently top the table after nine wins in their last 10 league outings, consigning their mid-season crisis to just another hyperbole in the depths of distant memory.

A 6-1 annihilation of Rayo Vallecano sent them to the summit, with Lionel Messi once again the combatant as he added a record-breaking 24th La Liga hat-trick to his seemingly endless list of records broken. Luis Enrique has silenced his doubters and has transformed a disjointed and querulous squad into one that is still challenging for silverware on three fronts following a run of 17 victories in their last 18 matches.

By contrast, Real are riding a 'crisis' storm of their own, having dropped points against lowly Athletic Bilbao and Villarreal. Despite a comfortable 2-0 win over a struggling Levante side, Real supporters left the Santiago Bernabeu embittered, for when you are Real Madrid, it's in games such as these where only a winning margin of four or five will suffice.

The unremarkable score line over Levante did little to appease fans, who have endured a turgid month with Los Blancos by their stratospheric standards, including a near-shock exit in the Champions League, as the defending champions narrowly avoided being eliminated from the tournament following a 4-3 home defeat at the hands of Schalke.

Barcelona's turnaround in form can be attributed to the return of Messi's enthusiasm, following the much-publicised bust-up with Luis Enrique. His potency in attack in this week's Champions League defeat of Manchester City once again served to outline that he is in superlative form. There is no secret to Barca's success; when Messi is happy, the team gets results.

But while it's easy to credit Messi, Neymar and Luis Suarez are also playing to their potential and their three-pronged attack is proving a compelling force.

Conversely, despite the array of attacking flair on display in the Real Madrid line-up, it appears that Carlo Ancelotti's policy of maintaining consistency in his starting XI is now resulting in tired legs and faltering psyche. Real's forwards are struggling to rediscover the consistency they possessed in the first half of the season. Gareth Bale has come under particularly vociferous attack from the Spanish press as he struggles to regain his form, though Karim Benzema and - more significantly - Cristiano Ronaldo are also below par.

Following Sunday's win over Levante, during which Ronaldo endured a frustrating night, Sport carried the headline, 'Madrid wins, Cristiano loses'.

Naturally, this will be yet another fierce and engrossing contest between these two intense rivals, and one which, like all others, is not short of intrigue. Anything can happen in 90 minutes, and while Football can be a fickle business and one where people are quick to forget and even quicker to judge, the prestige and momentum of an El Clasico transcends an average three point league win.