Barcelona head coach Xavi has called Sunday's El Clasico "the most important game of the season".
The Catalan outfit will enter the clash at Bernabeu in second position in the La Liga table, eight points behind the leaders Real Madrid with seven games left.
A win for Barcelona would cut the gap to five points with six to play, but a defeat would leave them 11 points off the summit and all but end their hopes of securing the trophy for the second successive season.
Xavi is expecting a difficult challenge against Real Madrid, with Carlo Ancelotti's side knocking Manchester City out in the quarter-finals of the Champions League on Wednesday night.
Barcelona, though, were unable to progress to the final four of the European Cup, with Paris Saint-Germain recording a 4-1 victory in the second leg of their quarter-final to advance.
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Xavi expecting tough challenge in El Clasico
"Tomorrow we have the chance to get back into La Liga. It happens to be the most important game of the season. We will find a strong Madrid and even more so after eliminating the best team in the world, City," Xavi told reporters during his pre-match press conference.
"The euphoria will be sky high and the opposition will be very strong. Today we trained well, yesterday we had a Champions League hangover. The team has all the enthusiasm in the world to fight for this league.
"Madrid had to defend against City, who are the best team in the world today. They had to defend and they defended very well. These are situations that you have to dominate and they also know how to do it.
"In the first half with us, they did well. They have potential, they know how to attack and make transitions.
"We talked about it today, that in the first few minutes of each half, Madrid will press. They are at home. We have to be very brave.
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A defeat would all but end Barcelona's La Liga title hopes
"It's the perfect stage to show personality. We've prepared well for the game, I think we can play well and win. The first few minutes will be key, calming the game and pressing high.
"They have won many times, because they are very good. I don't believe so much in luck. I believe in work, in the team, it's not by chance. Madrid, in the last three years, have knocked out the best team in the world twice.
"It's the most important game. We have to win to put pressure on them. If we win, we would be five points behind. They've lost one game out of 31, we don't have bad numbers either. I see it as an opportunity to get closer. We want to compete.
"We have to change our mindset. Let the anger, frustration and helplessness of the other day be turned in our favour. We have in front of us a strong Real Madrid, morally reinforced after this week in the Champions League."
Despite the disappointment of their Champions League exit last week, Barcelona are unbeaten in La Liga since the end of January and have won their last four in Spain's top flight against Mallorca, Atletico Madrid, Las Palmas and Cadiz.
Matt Law
