Madrid, Oct 7 (IANS): Sunday night sees FC Barcelona take on Real Madrid in the "Clasico", as the most important club game in world football has become known.

Barca go into the game eight points clear of Real Madrid after just six games of the BBVA Primera Liga season, knowing a win would land almost a knockout blow to their rivals' title ambitions, reports Xinhua.

Barca midfielder Xavi Hernandez said opening an 11 point lead would not be decisive in the race for the title with 31 games still to play, but given that Madrid have never made up and eight point deficit on Barca, he admitted such a lead would be "important".

However, it is one thing to speak about an 11 point lead and another thing altogether to achieve it: Barca and Madrid have already faced each other in the Spanish Supercup with Barca winning 3-2 in the Camp Nou Stadium, a win that would have been greater but for a huge error from Barca keeper, Victor Valdes.

The return leg saw Madrid defeat Barca 2-1 in the Santiago Bernabeu although Barca played much of the game with 10 men after Gerard Pique was sent off in the first half.

Pique is likely to miss Sunday's match with a muscle injury and his absence, along with Carlos Puyol is a major blow for Barca coach Tito Vilanova, whose side must play without their first choice central defenders.

Javier Mascherano and Alex Song will play in the heart of the Barca back line, but their unconvincing display together in last weekend's 3-2 win in Sevilla will give hope to Madrid strikers, Cristiano Ronaldo, Karim Benzema and Gonzalo Higuain.

Ronaldo goes into the match on the back of consecutive hat-tricks against Deportivo la Coruna and Ajax in the Champions League and he, along with Angel de Maria will be looking to exploit space left by Barca's attacking full backs Dani Alves and Jordi Alba.

Madrid may will also hope to exploit their height advantage and Pepe, Sergio Ramos and Ronaldo will all be a threat from set pieces such as corners.

The question mark hanging over the Madrid side is whether or not coach Jose Mourinho will keep faith with Kaka, who performed well in Amsterdam, or whether Luka Modric returns to the team in the attacking midfield role. Meanwhile Sami Khedira and Xabi Alonso will look to provide stability in central midfield.

Vilanova will hope to bring Andres Iniesta back after his substitute appearance against Benfica on Tuesday, while Pedro Rodriguez will provide pace and Leo Messi will lead the attack.

There are non-sporting issues surrounding the game and the recent surge in Catalan nationalist feeling will be reflected by an impressive mosaic in the Camp Nou in the colours of the Catalan flag. The fact is this happens just about every year, but this year it is something both Spanish and Catalan have chosen to focus on, with logically different viewpoints.

Whatever the politics, it is the football that will bring Spain just about to a halt Sunday evening as the nation sits to watch the latest round in the seemingly eternal duel between the two biggest clubs in Spain and quite possibly the world.