Of course, most of their fans would rather bump their car, drop a dumbbell on their toes, accidentally tell their true feelings to their boss about his or her skills or walk full tilt into a lamppost than lose to Spain's champions-elect. Again.
Including the Supercopa, Los Blancos are on a five-match winning streak against Barca, which has not happened in the living memory of most Camp Nou fans or employees.
But sometimes, especially in the midst of a crisis, it is vital to look at whether flaws are being corrected and whether the medicine is beginning to work, rather than thinking: Can everything be completely back to normal, immediately?
There are many deep-rooted and important issues that face Xavi's squad and the club as a whole; he -- and those who appointed him -- can see the light at the end of the tunnel, but they are by no means out of the darkness.
However, there are things to indicate that something exciting is being built, things that go beyond an arresting recent run of results, which has seen Barca climb to third in LaLiga, just five points behind Sevilla and with a game in hand.
While Xavi is the principal architect, people like Director of Football Mateu Alemany and his "special envoy" Jordi Cruyff have ensured that good, nourishing decisions have been made, particularly in a spectacular winter transfer market.
Nevertheless, the football health of a club is always predicated on results and performances and it is in this area which Xavi has shone.
Ahead of facing Madrid at what will be an ultra-hostile and schadenfreude-filled Bernabeu, Barcelona are undefeated domestically since December and have scored 24 times in their last eight LaLiga and Europa League matches.
But the most fundamental thing about Barcelona's upturn in fortunes is that Xavi has made the team competitive again and started the long process of reinstating the once-sacrosanct principles of possession and position.
Should you be in any doubt about Barca losing their competitive edge --becoming floppy rather than ferocious -- just think about the backdrop to the club's decline.
In addition to five straight Clasico defeats -- literally unheard of in modern times -- there was a series of absolute humiliations in Europe, with Bayern Munich Liverpool, Juventus, Roma and Paris Saint-Germain all having their way.
This season brought Champions League elimination before the knockout stages for the first time in two decades; Barcelona scored just twice in six group-stage games!
And while there is a litany of further examples, the punctuation point was an uncompetitive 1-0 defeat to Rayo Vallecano in October -- the first such result in 20 years -- after which then-coach Ronald Koeman expressed general satisfaction with what he had seen.
The upshot was that the Dutchman was summarily sacked before the Barcelona plane, in which he was travelling, returned to Catalunya, but the harsh fact is that the rust had set in for years.
Lionel Messi, Luis Suarez and Neymar brought glory and pantheon football, but they gradually imposed "their" standards and preferences for when training was staged and whether it began on time or not, as well as its intensity.
Neither Quique Setien nor Koeman corrected that atmosphere. Which, in stark terms, was a fundamental part of their job. Xavi, the legendary midfielder who returned as manager, had the option of arriving and reading the riot act.
The 42-year-old Catalan could have torn strips off most of the squad for one thing or another; announced it was his way or the highway and threatened them with being moved on.
He could have adopted short, sharp, shock tactics. It is probably what many fans and most media wanted. Instead Xavi's methods have been creative, surprising, popular and immensely successful.
The fundamental aims, since he took over in November, have been to make the squad fitter and sharper, to improve positional play and use of the ball and to both score, and win, more often.
Xavi believed there were three keys to achieving this, beginning with training sessions that were more intense and focused on specific team characteristics, traits that had been lost or dulled and which he wanted to be automatic once more.
The second key was to engage in targeted, clear one-on-one teaching and video sessions with most (although not all) of the squad, especially those who either had not grown up in the club's academies or who, if they had, were young and inexperienced.
The third key was, somehow, to add specifically identified talents during the January transfer window. A centre-forward, pace, width, experience and an on-field lieutenant in Dani Alves; overall, to bring an influx of goals, energy and winning mentality.
For the first aim, fitness coach Ivan Torres, who hails from Xavi's native Terrassa and who the boss has known since they were kids, has been fundamental. Simply, training sessions are now a marvel.
In years to come, when people tell the tale of their former midfielder triggering a resurgence in a club that was close to rock bottom, the analysis of how Barcelona trained will become textbook standard.
While in charge at Al Sadd in Qatar, Xavi and his staff learned how to get across methodology that, though utterly natural to them, was alien to most of their players. As such, delivery techniques, creative training routines and communication skills have been honed.
Torres' work includes lots of associative, fun, team-building exercises that look like the kind of thing you might have engaged in as a teenager at summer camp, but which have been effective.
Groups of players -- sometimes four, six or eight -- compete against one another on a range of tasks based on physical co-ordination, teamwork, speed of thought and hand-eye coordination.
Almost always with a basis of relays, teams are desperate to win, to laugh, boast and tease. Within that environment -- and without them really noticing -- is fostered intensity, agility, speed, spirit.
Moreover, Torres and Xavi believe such exercises at the beginning of a session have the effect not only of getting the squad buzzing, attentive and warmed-up athletically, but ready to learn and ready to engage in tactical and technical drills with more productive mindsets.
"Building up to a match, we always do team-building games," Nico Gonzalez recently told me. "Everyone likes competing and, if we do drills we enjoy, it's much more fun. I think that's very important in terms of feeling more united as a team and, ultimately, enjoying ourselves more."
In terms of the second aim, Xavi's fanatical devotion to watching, assimilating and assessing football matches far beyond his remit, either as a Barca player, Al Sadd coach or now, as main man at the Camp Nou, is a huge help.
While in Qatar, he enjoyed being in a bubble where his young family could grow happily and safely, while he "decompressed" after a lifetime playing at the top of the game.
Nevertheless, he watched endless matches, including all that involved Barcelona. It meant his compendium of knowledge, when he succeeded Koeman, was vastly superior to the Dutchman who had been in charge for the previous 14 months.
The result of this was to reduce timescale. Unlike most new managers, Xavi did not have to spend time watching, learning, coming to conclusions and then, weeks in, starting to correct what he did not like. He was primed from day one.
He has set up a programme of individual video tuition sessions for most of his players. Sometimes correcting positional flaws, sometimes about pressing and often about attacking space, but always to even the equilibrium between, for example, lifelong scholars of "the Barca way -- and former Xavi teammates -- like Gerard Pique, Jordi Alba, Sergio Busquets and newcomers of varying experience like Gavi, Sergino Dest, Memphis Depay and Pierre-Emerick Aubamayeng.
"Xavi is very intelligent; when he arrived at the club, he already knew everyone's strengths," Ronald Araujo recently told me. "From the very first moment, he has shown us videos explaining what he wanted from each of us. Once a week, we watch specific individual videos so as to continue improving.
"Xavi knew my abilities and told me that I would continue learning more and more about passing, positioning and more. Feeling supported by the coach is very important."
From thrashing Napoli away and Atletico at home, right down to narrow wins over lowly Elche and Alaves -- and even including January's Supercopa defeat to Madrid -- the absolute linking factor is that Barcelona compete.
If they are playing well and are fit and sharp, most opponents are going to suffer. If they are off the boil, or fall behind, they work coherently, aggressively and press to stay in a match. An awful trait to lose, it is a wonderful plus to have back.
Xavi's training of positional discipline contains drill after drill in which, to supplement the famous rondos, teams of eight will play in a large rectangular box, with three players in the middle operating as "jokers" for whichever team has the ball.
They are works of art. Pep Guardiola would recognise and approve. Maybe top up his own learning, even.
"Xavi has changed the team mentality, improved the individual players and recuperated the very essence of the Barcelona football philosophy," said club president President Joan Laporta, who has admitted he was wrong to say Xavi was not ready for the job just last May.
Meanwhile, though Xavi has a voice in transfers, credit there goes to Alemany and Cruyff for their nous, their contacts, their persuasive powers and their ability to negotiate. Their three in-season signings -- Dani Alves, Torres and Aubameyang -- have contributed 12 goals and six assists in all competitions.
However, even in these vastly improved times, when it is stimulating and interesting to watch Barcelona play, this remains an incomplete, uneven squad and the sign on the door should read: "Work in progress."
When he completed 100 days in charge last month, Xavi drily commented that they had been like "100 years" and, doubtless, the effort, the hours and the personal stake involved in curing his club will feel like that. But in actuality, he has made a couple of years' progress in a four-month spell.
When Xavi was in his pomp as a player, it was him -- not Messi, Suarez, Samuel Eto'o, Ronaldinho or anyone else -- who Iker Casillas, ahead of a Clasico, would want magically excluded from the Barcelona team.
It is asking a lot to suggest that the Xavi effect will immediately guarantee a return to winning ways on Sunday -- the odds favour Madrid -- but his team will compete. And that is a start.