Wednesday, F.C. Barcelona face their biggest test since Guardiola took over as coach.
The two goal deficit is the largest the team have had to overcome, and they will have to do it against a very solid, professional, and talented side. Indeed, nobody in Catalunya is underestimating the scope of the challenge.
"This is not a semifinal, this is a final," assert the Catalan press.
The fans have started Facebook groups, set up web pages, and used chains of texts and tweets to unite in their support. The players donned t-shirts with a message promising to "leave their skin on the pitch."
The task may be difficult, but they are not tilting at windmills. Mourinho's Inter is one dragon they are capable of slaying.
In order to do so, they must trust in their style of play.
In the past 12 months they have collected six trophies, and are on the doorstep of two more. This unprecedented achievement came through an unapologetic embrace of possession football.
The failure in the first leg was one of execution, not gameplan. Last week, Mourinho was successful in stopping a tired-looking Barcelona, but his team were never superior.
His selection of wide forwards stopped Barcelona's Brazilian fullbacks from overlapping, and deprived midfielders Xavi and Busquets of support. The two Catalan playmakers were also subjected to tight marking by Inter's midfield.
Like a bike with molasses in its gears, Barcelona's midfield struggled to find its normal rhythm. On occasions when it did, Inter players would commit tactical fouls to slow them down.
When Inter recovered the ball, they bypassed Barcelona's high pressure completely by playing long to the front three. Inspired performances by Eto'o, Sneijder, and Milito were critical in turning a match that could have ended with a different score.
As much as the press may fawn over Mourinho, and wax lyrical about his tactical genius, even he could not cope with Barcelona at the top of their game.
Earlier this season, in the group stage he scraped a draw in Milan by playing a caricature of defensive catenaccio football. At the Camp Nou they were casually brushed aside by a score of 2-0—exactly the scoreline needed tonight—with Messi and Ibrahimovic watching from the bench.
What Barcelona need is exactly what they displayed that night in November, energy and concentration.
The pass-and-move football played by Barcelona is not too different from previous footballing dynasties like Shankly's Liverpool, Michels's Ajax, or Sacchi's Milan.
When they play at their best, it looks like an effortless ballet of passes overwhelming a porous opposition defense. When they fail, they look predictable and naive, as they break against solid defenses and surrender weak goals.
The difference between the two outcomes is off-the-ball movement, picking the right pass, and quick recovery of the ball.
When all three are done well, the effect is cumulative. The opposition has to chase the ball more intensely and for longer, and has fewer chances for respite.
They tire a bit more, both mentally and physically. They begin to mis-hit passes and give the ball away cheaply. Spaces open up alongside, between, and behind their players.
The way Arsenal, Bayern, Lyon—and Inter last November—were demolished in under 40 minutes are examples of how devastating Barcelona is capable of being. The Spanish call it "the extra gear." When they reach their top-speed, no one can keep up.
Iniesta may be missing, Henry may be a shadow of his former self, the small squad may be fatigued from two packed seasons, but the Camp Nou will be a cauldron. If the players can replicate their previous great performances, they are sure bets to be in the Final in Madrid.