I wrote an analysis of the game, and there were several key areas in which Barca excelled: using width well, using a true No. 9 and winning the ball back in advanced areas.
This resurgence, after a genuine blip in form over the past month in which Jordi Roura's side lost three games in a row, settled the critics firmly back in their seats.
But how has this changed our perception of the Catalan club?
After the 2-0 defeat at the San Siro, and subsequent consecutive losses to arch-rivals Real Madrid, Barca were seen as rudderless, dead in the water.
But they fought back with a bang and made the necessary changes to stop Milan repeating the same heroic performance of three weeks previous.
David Villa, operating as a true No. 9, stole the attention of the two centre-backs, meaning Lionel Messi was free to drift around the pitch and influence the game in a manner he felt effective.
This, in addition to deploying two players touchline wide to stretch the pitch at the Camp Nou, resulted in Massimo Ambrosini and co. chasing shadows.
Messi was deployed as a No. 10, rather than a false-nine, for the first time in years, and this constitutes a "Plan B" many have yearned for over the past three or four seasons.
Messi plays the same role for Argentina
On the occasion that Barca do get stuck, what have they had to turn to?Internazionale bottle-necked them in 2010, Chelsea stumbled over the line in 2012. Barca had no answer to these blockades, but now one might have emerged.
And yet it's such an obvious answer, too—play David Villa in his natural position, up front.
Over the last few years, Barca have been haunted by one stigma: the tiki-taka passing game can be nullified by an extremely organised defensive setup.
This feeling was amplified by Milan's 2-0 shutout in the first leg, with Messi barely getting near the penalty area and Dani Alves getting nowhere close to the byline.
But the simple use of a true striker to trouble the centre-backs opens Messi's game up immeasurably. That's not to say Barca didn't benefit from other stellar performances from the likes of Jordi Alba and Sergio Busquets, but compare this Messi to the one at the San Siro and you'd think they were two different players.
With the wind in their sails, Barca have stemmed the flow of criticism headed their way. The teams who have progressed to the UEFA Champions League quarterfinals will dread the possibility of being drawn against the Catalan outfit.
No matter how impressive the comeback win was, the very fact that they were so easily stifled in one leg, and the fact Roura did nothing to fix it across the span of 90 first-leg minutes, is troubling.
The defence is suspect. M'Baye Niang should have scored after a shocking Javier Mascherano blunder.
Will Jupp Heynckes look at this side and think "they're beatable" or will he hope to avoid them until there is no other choice?
In B/R's Google Hangout before the game, Will Tidey asked the question: Who would you like to see in the final? Alexi Lalas said Bayern Munich vs. Borussia Dortmund, Matteo Bonetti said Milan vs. Juventus and I said Bayern Munich vs. Juventus.
No Barca.
A lot has been made of the Bundesliga's resurgence and the strength of both Bayern and Dortmund. Many believe Bayern to be the strongest outfit in the competition, others suggest Juve are impregnable.
Still no Barca.
Has this changed after Tuesday's resurgent performance?