Both clubs have made significant changes to their squads ahead of the 2026/27 season, with several players preparing to experience one of football's biggest rivalries for the first time.
Barcelona could feature six players making their Clasico debuts. New arrivals Dominik Livakovic, Rodri, Gabriel Jesus, Karim Adeyemi and Anthony Gordon are among those hoping to make an impact, while Brian Farinas has joined the first-team squad.
Xavi Espart could also make his first appearance against Real Madrid. The La Masia graduate was included in Barcelona's squad for last season's meeting but did not get onto the pitch.
Barcelona coach Hansi Flick will have to change at least four players from the starting line-up used in the most recent Clasico at Spotify Camp Nou. Marcus Rashford and Ferran Torres are no longer at the club, while Eric Garcia and Dani Olmo are unavailable because of injuries.
Real Madrid also have several new faces, with Yan Diomande, Marc Cucurella, Carlos Espí, Denzel Dumfries, Ibrahima Konate and Bernardo Silva among their new signings.
The biggest change, however, is in the dugout, where Jose Mourinho has returned for a second spell as Madrid coach. The Portuguese previously managed the Spanish giants between 2010 and 2013.
Madrid must make at least three changes to the side that started the previous Clasico. Fran Garcia and Gonzalo Garcia have left the club, while Vinicius Junior is suspended following his red card against Villarreal. Mourinho's recent team selections suggest there could be as many as seven changes.
The match will also mark the first Clasico meeting between Flick and Mourinho, although the coaches have faced each other before. Their only previous encounter came during the 2019/20 Champions League group stage, when Flick's Bayern Munich defeated Mourinho's Tottenham Hotspur 3-1.
Kingsley Coman, Thomas Muller and former Barcelona player Philippe Coutinho scored for Bayern in that match. The German side went on to enjoy a historic season, winning six trophies.
Flick has since built an impressive record against Real Madrid, winning six of his seven meetings with the club. Four of those victories helped Barcelona secure major honours, including two Spanish Super Cups, the Copa del Rey and the 2025/26 La Liga title.
His victories have come against three different Madrid coaches. Flick defeated Carlo Ancelotti four times, split his two meetings with Xabi Alonso with one win and one defeat, and beat Álvaro Arbeloa in their only encounter.
Mourinho, meanwhile, knows the pressure of facing Barcelona from his first spell at the Santiago Bernabeu. He contested 17 matches against the Catalan club between 2010 and 2013, recording five wins, six draws and six defeats.
That period included Barcelona's famous 5-0 La Liga victory in 2010/11 and the Champions League semi-final between the rivals in the same season. Their meetings were marked by intense competition and tactical battles.
Sunday's encounter carries significant importance in the league standings. Barcelona have won every La Liga match so far this season and sit top of the table, while Real Madrid are third, six points behind their rivals.
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Barcelona youngster Xavi Espart is relishing the chance to make his El Clasico debut against Real Madrid on Sunday and believes staying calm will be key to handling the occasion.
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Jose Mourinho has praised Real Madrid's squad depth after their 4-1 Champions League win over RB Leipzig but insisted his team must improve before Sunday's El Clásico against FC Barcelona.
