Barcelona boss Xavi Hernandez said winning Sunday's "El Clasico" in the Spanish capital is the only way his side can hold off Real Madrid's run to the La Liga title — the only remaining major silverware Barca could win this season.

Real, brimming with confidence after their Champions League win at Manchester City midweek, sit comfortably on top of La Liga on 78 points, ahead of Barca on 70 and Girona on 65. A win on Sunday would give Real an 11-point lead with only six games left.

"On Sunday we are playing for the league title. We have to win," Xavi told a news conference on Saturday.

"We have to manage our feelings and move on, let the frustration of the other day (elimination from the Champions League) which is difficult to digest turn in our favour. We will have a morale-strengthened Real Madrid in front of us. It will be the most important game of the season."

The last chance saloon has opened its doors early for battered Barcelona as they travel to Madrid after another European disappointment suffered midweek at home.

While Barca were knocked out of the Champions League, Real progressed with a shootout win at holders Manchester City on Wednesday.

Xavi praised Real for beating "the best team in the world" in Manchester City and said he will need a near-flawless performance by his side to leave the Santiago Bernabeu stadium with a win.

"We will face a Madrid with euphoria through the roof. We need to overcome the Champions League hangover and fight with all the enthusiasm in the world," Xavi said.

Real manager Carlo Ancelotti acknowledged that his side is edging closer to the title but said it all could change if they lose focus and take their old rivals lightly on Sunday.

"We are doing well. The cake is ready and all that remains is the icing on top," Ancelotti told a news conference on Saturday.

"Barca are still alive and will be very competitive opponents who are doing very well despite the PSG loss. We're convinced that it's going to be a usual Clasico, hard fought."