The nine-times European Cup winners were overwhelmed 4-1 by a dynamic Borussia Dortmund in their semi-final first leg on Wednesday, though Cristiano Ronaldo's away goal gives them a glimmer of hope for the return at the Bernabeu next Tuesday.
Barca's injury problems and inconsistent form had been more apparent before their 4-0 defeat at Bayern Munich on Tuesday, while Real appeared to have geared all their planning towards their bid for a 10th European crown.
"Extraordinary. In two days the top two in the class have been swept aside," said the editorial in Madrid-based sports daily AS on Thursday.
"It almost impressed me more what happened yesterday, because I never remotely considered the possibility of it."
Mourinho has openly conceded defeat in the defence of their La Liga title for months, saying their priority was Europe and the Copa del Rey, where they meet Atletico Madrid in the final on May 17.
In recent weeks, he has fielded weakened sides in the league to conserve the energies of an expensively assembled and almost injury-free squad.
They trail leaders Barca by 13 points with six games remaining and could see their arch-rivals secure the trophy this Saturday, if the Catalans win at Athletic Bilbao and Real lose the city derby at Atletico.
Captain Sergio Ramos's pitchside comments at the end of the game, when he said: "We lacked commitment, starting with myself and including the 10 others who were on the pitch," were also surprising.
Mourinho defended Ramos saying the words came out in the heat of the moment.
"I prefer to say they wanted to, but weren't able to compete," the former Chelsea and Inter Milan boss told Spanish television, as he admitted they had been outclassed individually and as a team.
Madrid-based sports daily Marca described Real's display as "lamentable" and said it was "perhaps the worst Madrid of the Mourinho-era since their 5-0 defeat at the Nou Camp (2010)".
Mourinho was brought to Madrid principally to challenge Barcelona's hegemony, and over two-and-a-half years he has built a team that can now claim to have the edge over their rivals in head-to-head meetings.
Whether that counter-attacking style against a side who dominate possession is enough to succeed on the European stage is another question, as Real struggled to break down a Dortmund team who used the same quick-breaking tactics against them.
Not only were Real physically overpowered, they were found to be wanting tactically too.
The fact that Real continue to lie second in La Liga behind Barca, both having turned their attentions to Europe of late, raises the question again about the quality of Spain's domestic competition.
Unlike in other major European leagues there is no collective bargaining for the sale of La Liga television rights, though changes are being pushed through by the Spanish government.
Under the current system, Real and Barca, the world's richest clubs by income, split around half of the total pot of 650 million euros for the league rights between them.
Their domestic rivals, many of whom are in dire financial straits, are left to fight over the scraps and find it impossible to compete with the two heavyweights.
It is still early, however, to write off Real's hopes of making the Champions League final, as they are unbeaten at home in all competitions since January 2012.
"Real have an international reputation precisely because of their second-leg performances," former player and club director Emilio Butragueno told broadcaster Canal Plus.
"If we were able to do it, so can they."
- Sports & Recreation