Barca were thumped 4-0 away by an impressive Bayern Munich in their first leg on Tuesday, putting in one of their most toothless displays in recent memory.
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On Wednesday, they were greeted with newspaper headlines such as 'Historic beating' in Madrid-based daily Marca, 'Catastrophe' in Barcelona-based Mundo Deportivo, and 'Azulgrana Waterloo' in daily El Mundo.
The Barca players looked dazed and downcast as they spoke to reporters in the mixed zone, and lacked conviction when asked about their chances of turning the result around at the Nou Camp next Wednesday.
"They were better than us, they were much stronger. They beat us in everything and were superior," World Player-of-the-Year Messi told reporters.
"A comeback is difficult, Bayern are a very good team. We have to lift ourselves, try to secure the league title and try to turn this round. If we can't, we need to start thinking about next season."
Barca could be crowned La Liga champions for the fourth time in five years if they can beat Athletic Bilbao on Saturday, and Real Madrid lose the city derby at Atletico.
The Argentine forward has been the outstanding figure in the Barcelona side that won the European Cup in 2009 and 2011, his goals helping them to a sixth consecutive Champions League semi-final, but he was a barely noticed presence in Munich.
Messi suffered a hamstring injury against Paris Saint-Germain in the quarter-final first leg, and after making a decisive substitute appearance to help Barca through the second leg two weeks ago, he has not played.
On Monday, he was given the all-clear to feature against Bayern, but on the pitch he looked short of spark and energy as he was crowded out time and again.
"I haven't played for a long time, but I felt fine," Messi said when asked about his fitness.
LACK OF FAITH
While Messi faltered, Barca coach Tito Vilanova's lack of faith in his alternatives up front was startling.
He did not make a substitution until the 83rd minute, bringing on striker David Villa for Pedro, by which time his side were already 4-0 down. His other two possible changes were not made.
Asked if the side were too reliant on Messi, Dani Alves retorted: "The debate on our 'Messi-dependency' only appears when we lose.
"It will be very difficult [to turn around]," the Brazil defender added. "But if we have to fall, let us do it with our heads held high. We haven't said the last word in this."
Barca came back from a 2-0 first-leg reverse to defeat AC Milan 4-0 at home in their last 16 tie in March, but the latest defeat felt more decisive.
Barca have famously shunned talk of a Plan B when their trademark passing game fails to produce the goods, simply saying they need to sharpen and improve Plan A.
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