Having been thoroughly defeated 4-0 in the first leg of the quarterfinal, Dortmund had nothing to fear on Tuesday and launched an aggressive assault on Barcelona from the outset, catching the visitors unprepared.

Barcelona coach Hansi Flick, who has a lot of experience playing against and beating Dortmund from his time in the German league, said the strong home crowd meant he thought the second game would be difficult even though his team was four goals ahead.

"I had a premonition that something of this nature was imminent," Flick stated to broadcaster Amazon Prime. "Today, one must commend Dortmund for a superb performance, and similarly, offer congratulations to my team for reaching the semifinals."

It proved to be an uncharacteristically subdued performance for Barcelona's prolific forwards, Raphinha and Robert Lewandowski, who had amassed 12 and 11 Champions League goals respectively this season. The nearest either player came to finding the net was a rather feeble attempt by Raphinha directed at Dortmund goalkeeper Gregor Kobel.

Guirassy is Dortmund's "vital lifeline," coach Niko Kovac said after a game that helped his rising reputation and put him at the top of the Champions League scoring list this season.

Dortmund had arguably forfeited the quarterfinal in the initial leg and were further hampered by the absence of captain Emre Can and midfielder Carney Chukwuemeka, who had both been sidelined due to injuries earlier that day.

For a period, Guirassy appeared to defy the odds.

Despite having squandered opportunities in the initial leg and passed up further chances early on Tuesday, Guirassy made amends 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, and an own goal by Ramy Bensebaini further complicated Dortmund's challenge. Fermín López's low cross deflected into the net off Bensebaini's ankle — a double setback for Dortmund, particularly as the defender had been instrumental in their attempted resurgence, having assisted Guirassy's second goal moments earlier.

Capitalizing on Ronald Araujo's defensive miscue, Guirassy netted his third goal in the 76th minute with a forceful strike from within the penalty area, thereby claiming the title of the Champions League's leading goalscorer this season with a tally of 13.

This outcome reignited Dortmund's aspirations for a Champions League resurgence, potentially ranking among the most remarkable comebacks in the competition's history, akin to Barcelona's memorable triumph over Paris Saint-Germain in 2017; however, Barcelona ultimately maintained their advantage to advance.

Barcelona is set to face either Inter Milan or Bayern Munich in the semifinals, marking their first appearance in the Champions League's final four since the 2018-19 campaign. Concurrently, in Tuesday's other fixture, PSG secured their semifinal berth with a 5-4 aggregate victory over Aston Villa, notwithstanding their 3-2 defeat in the second leg.

Beyond marking Barcelona's initial defeat across all competitions since their 2-1 loss to Atletico Madrid on December 21, this result also represented their first Champions League setback since September.

Remarkably, it was merely the seventh loss sustained during Flick's tenure of 50 matches at the helm. The German tactician had previously emerged victorious in all seven encounters against Dortmund while managing both Barcelona and Bayern.

Dortmund may face a considerable delay before hosting a Champions League match and hearing its iconic anthem.

Last year's Champions League finalist currently sits eighth in the Bundesliga with five fixtures left, six points adrift of the four Champions League qualification spots.