Real Madrid were able to record an easy 3-1 win over Barcelona when the two sides met at the Bernabeu earlier this season.
However, it will certainly be a very different story this time around as there has been a clear contrast in the form of these two teams of late.
The Los Blancos have been struggling of late, getting knocked out of the Copa del Rey, barely managing to get through to the last eight of the Champions League and surrendering their top position in the La Liga to Barcelona.
Defeat to Barcelona in Sunday's El Clasico could prove to be fatal blow to Real Madrid La Liga title aspirations as they would then be four points behind the Catalans, with only 10 matches left to play.
However, Real boss Carlo Ancelotti despite admitting that Sunday's Clasico is an important fixture for both sides, insists that his side's Champions League quarter-final against Madrid rivals Atletico is more "decisive."
"This is just an important game for Madridistas. It is the same for Barcelona. Both teams have a global image to live up to and have to give a good impression," the former boss told Goal. "But this match won't be as decisive as the Champions League tie against Atletico."
Although the former AC Milan admits that Real Madrid have been in good form of late, he insists that the confidence in his side is "exactly the same as it was before."
"We haven't played well recently but our confidence is exactly the same as it was before. The players are calm and confident and ready to put in the best game possible."
"The atmosphere in the dressing room is different because this is a special game. We are playing a great side at an important moment of the season."
Barcelona, on the other hand, will also be very confident ahead of this fixture as they have been in fine form of late.
Propelled by their three South American attackers Lionel Messi, Neymar and Luis Suarez, the Barcelona juggernaut have been doing very well in all the competitions so far.
While Barcelona have managed to successfully replace Real Madrid at the top of the La Liga, they have also managed to reach the final and the quarter-final of the Copa del Rey and the Champions League respectively.
A victory against Real Madrid on Sunday would certainly give an advantage to Barcelona in the title race.
But Barcelona boss Luis Enrique, like Ancelotti, feels that Sunday's El Clasico is "important", but not "decisive".
"It's an important game, but not a decisive one," Enrique told Barcelona's official website. "There are still ten very difficult games ahead of us... But games with Madrid are certainly different to any others."
"They are our eternal rivals and the closest team to us in the table. If we win, it also means they get no points, and there's also our head-to-head goal difference to bear in mind. There's a lot to look forward to."
The former Celta Vigo boss insists that there are "no clear favourites" on Sunday even though he admits that their "home advantage" will give Barcelona an "extra boost."
"There are no clear favourites in games like these. These are two top quality teams with a lot at stake. But we do have home advantage and playing in front of our own fans always gives us that extra boost".
"We won't fall into the trap of thinking it will be easy. We know the defence will be under serious pressure at times and we hope the fans can focus their excitement on helping us when things like that happen."
Barcelona: Bravo; Alves, Pique, Mathieu, Alba; Mascherano, Iniesta, Rakitic; Neymar, Messi, Suarez
Real Madrid: Navas; Carvajal, Pepe, Ramos, Marcelo; Kroos, Modric, Isco; Bale, Benzema, Ronaldo
Where to Watch Live
The El Clasico is set to begin at 9pm local time (1:30am IST, 8pm GMT, 4pm ET) with live coverage in India on Star Sports 4 and Star Sports HD4. Viewers in India can also catch all the action via live streaming online on Starsports.com.
Viewers in the UK can catch all the action on Sky Sports 1 and Sky Sports 1 HD, while the option to live stream is on Sky Go. The game will be shown live in the US and Canada on Bein Sports USA and Bein Sports Canada respectively with the live streaming option on Bein Sports Connect.
Viewers in the Middle East and North Africa can catch the match on Bein Sports Arabia or Bein Sports Connect, while the audience in Australia can enjoy the action live on Fox Sports 4 and Foxtel Play.