MADRID, March 17 (Xinhua) -- FC Barcelona entertain Real Madrid on Sunday night in what could well be the most decisive match of the current La Liga season.

Barca receive Real Madrid at the Camp Nou Stadium with a nine-point lead at the top of La Liga, knowing that a win would put them 12 points clear of their closest rivals in the title race with just 12 games left to play, all but assuring this season's La Liga crown.

Even a draw would see Barca keep their lead and leave Real Madrid with a virtual mountain to climb if they want to retain their title.

This is the fourth meeting between the two teams this season and the third in two months, following Barca's 3-1 win in the Spanish Supercup in January and a 1-0 win in the Santiago Bernabeu in the Copa del Rey semifinal first leg at the start of March.

Those two matches showed two completely different sides of Barca, as they beat Madrid in the Supercup with a display of controlled and aggressive passing football, that allowed their rivals few options.

The Copa del Rey saw Barca play a completely different game as they surrendered possession to their rivals and defended deep.

Barca coach Xavi Hernandez was without key players Andreas Christensen, Robert Lewandowski, Pedri and Ousmane Dembele for that game.

Real Madrid's only injury worry is over defender David Alaba, although Karim Benzema did pick up a slight knock on his ankle as he scored the winning goal in Wednesday's Champions League win over Liverpool.

The match has been conditioned by revelations that FC Barcelona made payments over a long period of time up to 2018 to Enriquez Negreira, a former referee and vice-president of the Spanish referee's technical committee.

Although the club said the payments were for technical reports, the implication is they were also aimed at influencing referee's decisions, and the case is now being investigated by Spain's State Prosecutor.

Real Madrid have joined the prosecution on an individual level, in a decision that has soured relations between two clubs that are key in the development of any future 'Superleague' and that is likely to lead to a more hostile than usual atmosphere in the Camp Nou.

The Negreira case also means that any decision taken by match referee, Ricardo De Burgos Bengoetxea will be looked at under the spotlight.