Following a decisive 4-0 defeat in the initial quarterfinal match, Dortmund, with nothing left to risk on Tuesday, adopted an aggressive approach from the outset against Barcelona, destabilizing the visiting team.

Barcelona's coach, Hansi Flick, who has a lot of experience playing against and beating Dortmund from his time in the German league, said that the strong support from the home fans meant he expected a difficult second game, even though his team was leading by four goals.

"I had a certain premonition that such an outcome was probable," Flick disclosed to broadcaster Amazon Prime. "One must commend Dortmund today for their excellent performance, and similarly laud my team for securing their place in the semifinals."

It proved to be an uncharacteristically subdued performance from Barcelona's prolific attacking duo, Raphinha and Robert Lewandowski, who had netted 12 and 11 Champions League goals respectively this season. The closest either player came to breaking the deadlock was a rather meek attempt by Raphinha, directed straight at Dortmund's custodian, Gregor Kobel.

Guirassy has become Dortmund's indispensable asset, according to coach Niko Kovac following a match that further cemented his burgeoning reputation and propelled him to the top of the Champions League scoring charts this season. "Serhou, like any forward, simply requires his teammates' backing, and he received that today."

Dortmund had arguably sealed their elimination from the quarterfinal in the initial leg and, compounding their difficulties, captain Emre Can and midfielder Carney Chukwuemeka were both sidelined by injuries earlier that day.

Temporarily, Guirassy defied expectations.

Guirassy, having previously failed to convert opportunities in the first leg and squandered further chances early in Tuesday's match, capitalised from the penalty spot in the 11th minute following a collision between Barcelona goalkeeper Wojciech Szczesny and Pascal Gross.

Guirassy's header extended the lead to 2-0 in the 49th minute, preceding a Ramy Bensebaini own goal from Fermín López's low cross that further complicated Dortmund's predicament. This proved particularly detrimental as Bensebaini had been instrumental in the attempted comeback, having assisted Guirassy's second goal moments earlier.

Capitalising on Ronald Araujo's defensive lapse, Guirassy sealed his hat-trick in the 76th minute with a potent close-range strike, thereby claiming the title of the Champions League's leading scorer this season with 13 goals.

This turn of events rekindled Dortmund's aspirations for a remarkable comeback in the Champions League – a potential feat comparable to Barcelona's notable recovery against Paris Saint-Germain in 2017 – however, Barcelona maintained their lead and advanced.

Barcelona is poised to confront either Inter Milan or Bayern Munich in the semifinals, marking their first appearance in the Champions League's penultimate stage since the 2018-19 campaign. In the other fixture on Tuesday, PSG secured their place in the semifinals with a 5-4 aggregate triumph over Aston Villa, notwithstanding their 3-2 defeat in the second leg.

This outcome marked Barcelona's initial defeat across all competitions since their 2-1 loss to Atletico Madrid on December 21st. Furthermore, it represented their first Champions League reverse since September and only the seventh setback in Flick's fifty matches at the helm. The German manager had previously secured victories in all seven of his encounters with Dortmund, while in charge of both Barcelona and Bayern.

Dortmund may have to await the return of the Champions League anthem to its stadium for some time.

With five matches left in the Bundesliga season, last year's Champions League finalist currently sits in eighth place, six points adrift of the four coveted Champions League qualification spots.