El Clasico is one of world football's most iconic games, with past encounters giving football fans some of the most gruesome and exhilarating moments in the history of the sport.
The two sides will meet once again this weekend, with - as expected - a huge amount at stake. A win for Barcelona would see them go 14 points clear of Real Madrid before Christmas and Real - who recently won the FIFA Club World Cup - will go into this game knowing that they must win in order to make up ground on their rivals.
Here's a look at three key battles that could decide the game between Spain's two giants.
3. Sergio Busquets vs Casemiro
These two holding midfielders will arguably have the most important role to play in this weekend’s Clasico.
Busquets has been pivotal in his role for nearly a decade and has always shown consistent composure when he’s on the ball. His distribution is also second to none, and when he's in possession he is constantly looking to put Barcelona on the front foot.
The Spaniard will be aware that he has the experience advantage over Casemiro, but the Brazil international’s physical and attacking prowess makes him a tough match for Busquets. Casemiro is aggressive in his play and isn’t shy of a tackle or two, which could catch the Barca midfielder off guard if he’s not careful.
2. Cristiano Ronaldo vs Gerard Pique
Cristiano Ronaldo has had a fairly underwhelming Primera Division campaign so far - scoring just four times in 11 games. However, if there was ever an occasion to get the best out of CR7, it’s most certainly a Clasico.
He often performs to the best of his abilities when it comes to the biggest games of the season, and what’s bigger than a must win Clasico for Ronaldo and Real Madrid. The Portuguese forward knows that there can be no leniency when Madrid are attacking, but Gerard Pique will try his best to make sure Ronaldo has a quiet afternoon.
Pique has been part of a defence that has conceded just seven goals – the joint best in Europe’s top five leagues - in La Liga this term. Pique will want to impose himself by using his physical attributes to try and stop Ronaldo and co., but he will be aware that he's in for a busy afternoon.
1. Marcelo vs Lionel Messi
Lionel Messi has the most goals of any player in Clasico history with 24, and not many people are more aware of the Argentine’s abilities than left-back Marcelo. The Brazilian full-back has been at Madrid for a decade now, and will still find it extremely difficult to cope with the lively number ten.
Messi has had an eventful first half of the season - scoring 20 goals in 26 games in all competitions and hitting the woodwork more than a dozen times. He knows that if he can help his teammates in claiming victory then he’ll see his beloved Barca go 14 points clear of rivals Real after just 17 games.
Marcelo will need to bring his A-game if he hopes to have any chance of curtailing the threat which Messi poses, while trying to support Ronaldo in Los Blancos' attack.