Holders Barca were dumped out of the Copa del Rey by their arch-rivals on Tuesday, suffering a humiliating 3-1 semi-final second-leg battering in front of their own fans, to miss out on a place in the final.
With the defeat coming hot on the heels of their lame 2-0 Champions League last-16 first-leg reverse at AC Milan last week, alarm bells have been ringing at the Nou Camp as Barca's season threatens to run out of steam.
They hold a 12-point lead over second-placed Atletico Madrid in the league, and a 16-point advantage over Real in third, but Barca are a side used to winning more than one title a year and anything less will spark talk of a decline.
On the other hand, Real, who have written off their chances of retaining their league crown, come out of the semi-final reinforced psychologically and with their eyes firmly fixed on their quest for a 10th European Crown.
Coach Jose Mourinho is sure to rest players with a trip to Manchester United in their Champions League last-16 tie looming on Tuesday, when Real need to build on a 1-1 draw from the home leg.
On Wednesday, Barca president Sandro Rosell flew to New York to see coach Tito Vilanova, who is managing the team from afar while he continues his recovery from a second bout of surgery on his saliva glands in December.
Pep Guardiola's former assistant had a tumour removed from his glands in November 2011 and is not expected to return until mid-March.
"It isn't easy without the presence of the first-team coach," Barca and Spain midfielder Andres Iniesta told a news conference on Wednesday.
"It's been a long time and it's one more hurdle we have had to get over this season.
"We don't need him to return immediately now we have lost a couple of games. His health comes first, and we have confidence in those who are here."
Assistant coach Jordi Roura has taken the reins since the turn of the year but Barca have looked predictable at times, lacking width and pace, while the defence has leaked goals.
In a bid to freshen up the side, Roura could opt to play winger Cristian Tello and striker David Villa from the start at the Bernabeu, with attacking midfielder Cesc Fabregas making way.
The move could free up space for World Player of the Year and leading scorer Lionel Messi, who missed training on Wednesday with a fever, after uncharacteristically low-key performances against Milan and Real.
"We need to think hard about the two games we have lost, what we did well and where we can improve," Iniesta added.
"We need to recover the sensation of being a compact and infallible team and I am convinced we can do this.
"We shouldn't forget we are leaders in La Liga and we should try to maintain our advantage."
Real will be without suspended winger Angel Di Maria for a 'Clasico' overshadowed by their trip to Old Trafford.
A readers' survey on the Madrid-based sports daily AS website on Thursday saw fans voting overwhelmingly for Real to field a team of substitutes.
Atletico, who set up a Cup final with their city rivals Real by overcoming Sevilla 4-3 on aggregate on Wednesday, visit fourth-placed Malaga on Sunday (1800 GMT) holding a 14-point advantage over their hosts.
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