Following a comprehensive 4-0 defeat in the initial quarterfinal match, Dortmund, with nothing to jeopardise, assailed Barcelona from the outset on Tuesday, unsettling the visiting team.

Barcelona coach Hansi Flick, who has a lot of experience playing against and beating Dortmund from his time in Germany, said the enthusiastic home fans meant he expected a difficult second game even though his team was four goals ahead.

"I had a sense that something of this nature was imminent," Flick conveyed to broadcaster Amazon Prime. "Today, one must commend Dortmund; they delivered a commendable performance, and my team deserves recognition for reaching the semifinals."

It proved to be an uncharacteristically subdued performance from Barcelona's usually prolific forwards, Raphinha and Robert Lewandowski, who had netted 12 and 11 Champions League goals respectively this season. The nearest either player came to registering a goal was a rather meek effort from Raphinha, easily gathered by Dortmund's goalkeeper, Gregor Kobel.

Following the match that further solidified his burgeoning reputation and propelled him to the top of the Champions League scoring charts for the current season, coach Niko Kovac lauded Guirassy as Dortmund's "life insurance." Kovac further remarked, "Serhou, like any forward, simply requires the backing of his teammates, which he received today."

Dortmund had arguably jeopardised their quarterfinal hopes in the initial leg and, in addition, had captain Emre Can and midfielder Carney Chukwuemeka sidelined due to injuries earlier that day.

For a period, Guirassy appeared to render the improbable achievable.

Guirassy had missed chances in the first game and missed more chances early in Tuesday's game, but he scored from the penalty spot in the 11th minute after Barcelona goalkeeper Wojciech Szczesny crashed into Pascal Gross.

Guirassy's header extended the lead to 2-0 in the 49th minute, prior to an own goal from Ramy Bensebaini that significantly complicated Dortmund's situation. Fermín López's low cross deflected in off Bensebaini's ankle – a particular setback for Dortmund, as the defender had been pivotal in their endeavour to stage a recovery, having assisted Guirassy's second goal moments before.

Guirassy capitalised on Ronald Araujo's defensive lapse to secure his hat-trick with a forceful close-range strike in the 76th minute, thereby establishing himself as the Champions League's leading scorer this season with 13 goals.

This result instilled in Dortmund renewed confidence in achieving what would have been a historic Champions League turnaround, a feat comparable to Barcelona's against Paris Saint-Germain in 2017, but Barcelona ultimately prevailed and advanced.

Barcelona is set to confront either Inter Milan or Bayern Munich in the semifinals, marking their return to this stage of the Champions League since the 2018-19 campaign. Concurrently, in the other fixture on Tuesday, PSG secured their place in the semifinals by overcoming Aston Villa with a 5-4 aggregate score, despite suffering a 3-2 defeat in the second leg.

The 2-1 loss to Paris Saint-Germain was Barcelona's initial defeat in any competition since falling to Atletico Madrid on December 21st, ending an extensive unbeaten sequence across various tournaments.

Dortmund may face a protracted wait before the Champions League anthem resonates through their stadium once more.

The club that reached the Champions League final last year currently sits in eighth position in the Bundesliga with only five matches left to play, trailing the spots that qualify for the Champions League by six points.