La Liga preview: El Clasico dominates Spanish top flight
Alex Song and Javier Mascherano are set to play in central defence for Barcelona against Real Madrid due to Carlos Puyol's dislocated elbow.
Puyol dislocated his elbow when he landed awkwardly after going for a header in Barcelona's 2-0 Champions League win over Benfica on Tuesday and the Catalan club's head coach Tito Vilanova is likely to play Song and Mascherano in Sunday's El Clasico versus Real Madrid.
Song and Mascherano are both more known as defensive midfielders but with regular central defenders Puyol and Gerard Pique injured and Eric Abidal still recovering from a liver transplant, Vilanova believes he has no other option.
"I have always said it, we have always had problems in central defence but we will get through it," Vilanova said.
Real Madrid manager Jose Mourinho will be thrilled at the prospect of sending Cristiano Ronaldo and Gonzalo Higuain out against Barcelona's improvised defence.
Mourinho's side have started their La Liga campaign slowly with three wins and a draw from six games but thumped Ajax Amsterdam 4-1 in the Champions League on Wednesday with Ronaldo scoring a hat-trick and Karim Benzema also getting on the scoresheet.
Sunday will also see second-placed Atletico Madrid host Malaga, who are third in La Liga's standings, with the former set to go top of the league if they win and Barcelona lose.
But Atletico Madrid will take on the best defensive side in Spain's top tier with Malaga having conceded just two goals this season.
Malaga head into the game on the back of a 3-0 win away to Anderlecht in the Champions League to continue their perfect start to the continental club competition.
Celta Vigo and Sevilla will get the weekend's La Liga action underway on Friday, while on Saturday, Rayo Vallecano host Deportivo La Coruna, Real Zaragoza face Getafe, Valladolid will play Espanyol and Real Betis take on Real Sociedad.
In other fixtures, Levante host a derby clash with Valencia, Granada travel to Mallorca and Athletic Bilbao are up against Osasuna.