Having suffered a comprehensive 4-0 defeat in the initial quarterfinal encounter, Dortmund adopted a no-holds-barred approach on Tuesday, initiating aggressive offensive maneuvers against Barcelona from the outset and thus unsettling the visiting squad.

Hansi Flick, the Barcelona tactician, drawing upon his extensive Bundesliga experience of confronting and overcoming Dortmund, averred that the fervent home support presaged a formidable second leg, notwithstanding his squad's four-goal advantage.

Flick disclosed to the broadcaster Amazon Prime, "I harboured a certain presentiment that such an eventuality was imminent." He continued, "Today, one is compelled to laud Dortmund for their superlative performance, and equally, my own contingent for having clinched their place in the penultimate round."

In an atypical turn of events for Barcelona's customarily potent attacking duo, Raphinha and Robert Lewandowski—whose individual tallies in the Champions League campaign stood at a formidable twelve and eleven goals, respectively—the match transpired with an unusual dearth of offensive contributions, their most notable albeit modest attempt being a rather insipid strike from Raphinha directly at Dortmund's custodian, Gregor Kobel.

Guirassy embodies Dortmund's "life insurance," as articulated by coach Niko Kovac following a match that underscored his precipitous ascent to prominence and positioned him at the apex of the Champions League scoring charts this season. "Serhou necessitates merely the unwavering support of his teammates, a prerequisite for any striker, and that was unequivocally furnished today."

Dortmund had arguably forfeited the quarterfinal tie in the initial leg, compounded by the pre-match infirmity exclusions of skipper Emre Can and midfielder Carney Chukwuemeka.

For a duration, Guirassy rendered the ostensibly insurmountable a tangible prospect.

Guirassy, having squandered opportunities in the inaugural leg and subsequently spurned a further brace early in Tuesday's fixture, evinced faultless execution from the penalty mark in the eleventh minute following an untimely collision between Barcelona's custodian, Wojciech Szczesny, and Pascal Gross.

Guirassy's decisive header, establishing a two-goal advantage in the forty-ninth minute, was swiftly followed by Ramy Bensebaini's calamitous own goal, rendering Dortmund's prospects considerably more arduous; this defensive misadventure, a consequence of Fermín López's low cross deflecting cruelly off Bensebaini's ankle, represented a compounding of misfortune for Dortmund, particularly given the defender's prior, instrumental role in galvanising their attempted resurgence, having furnished the assist for Guirassy's preceding strike.

Exploiting a defensive lapse by Ronald Araujo, Guirassy completed his hat-trick in the seventy-sixth minute with a forceful close-range strike, thereby ascending to the apex of the Champions League's scoring charts for the current season, registering thirteen goals.

This turn of events afforded Dortmund a glimmer of aspiration concerning the potential consummation of what would have constituted one of the most remarkable Champions League reversals in history — a feat commensurate with Barcelona's notable vanquishing of Paris Saint-Germain in 2017 — yet Barcelona ultimately persevered, securing their advancement.

Barcelona is set to confront either Inter Milan or Bayern Munich in the semifinals, marking their first appearance in the penultimate round of the Champions League since the 2018-19 campaign; concurrently, Paris Saint-Germain secured their berth in the semifinals by virtue of a 5-4 aggregate triumph over Aston Villa, notwithstanding a 3-2 defeat in the reverse fixture.

Beyond marking Barcelona's inaugural defeat across all competitive fronts since their 2-1 capitulation against Atlético Madrid on December 21st, this reverse represented their première Champions League setback since September, and constituted only the seventh loss in Flick's half-century of matches at the helm, with the German tactician having hitherto secured victories in all seven prior encounters against Dortmund during his tenures presiding over both Barcelona and Bayern.

Dortmund may face a protracted interlude before the UEFA Champions League anthem once again resonates within the confines of its ground.

The UEFA Champions League finalist of yesteryear languishes in eighth position within the Bundesliga standings, with but five fixtures left to play, and a six-point deficit separating them from the quartet of coveted Champions League qualification berths.