They will remember this as the 'dogs of war' night in Leicester City's history - the night they unleashed havoc upon another European reputation of considerably higher standing than their own, although no team ever reached the quarter-finals of the Champions League with only a snarl.
There was great quality on another remarkable chapter in the Leicester story, one in which they allied their formidable team spirit to the old principles of counter-attack and plunder that won them the Premier League title last season.
"Let slip the dogs of war," proclaimed the pre-match banner with a nod to the literary namesake of their new manager Craig Shakespeare, and so they beat one of the most consistent teams in Europe of recent years.
The draw for the last eight awaits on Friday, and what a way to reach it for the English champions with goals from Wes Morgan and Marc Albrighton, as well as a penalty save from Kasper Schmeichel.
They went for the jugular in the way that was second nature last season and took advantage of a Sevilla team whose recent slip of domestic form has come at a bad time.
The Spanish side were poor indeed, and you could tell in their manager Jorge Sampaoli that this was a bad day. He was sent to the stand by the Italian referee and before then his team had gone down to 10 men with the dismissal of Samir Nasri.
And, even worse, Steve N'Zonzi missed a second-half penalty that would have taken the game to extra-time. By the full-time whistle, with former midfielder N'Golo Kante waving from the stands and the chairman Vichai Srivaddhanaprabha looking delighted, it felt a long time since the sacking of Claudio Ranieri - although the tears or injustice for him were shed away from the King Power.
It started with that unusually decorative tifo display for an English crowd, the Shakespeare quotation alongside a picture of the Leicester manager of the same name who, it should be said, is not the most instantly recognisable man in the game - at least not yet.
This was Leicester's way of saying they were up for it, and that was evident in the way they pressed Sevilla once the home team had found their feet although not before Schmeichel has saved low to his left to stop Nasri's shot.
The Frenchman is a big part of what makes Sevilla tick but the constituent parts of this fine side were not running smoothly in the first half, under pressure from Leicester. The likes of N'Zonzi and Vitolo were chased all through the first half but it was in their three-man defence that Sevilla struggled the most.
Adil Rami could not cope with Jamie Vardy's pace, and the midfielder and captain Vicente Iborra was booked for one of those tackles which connects a second after the England striker has nudged the ball away.
That was the free-kick from which Leicester created their goal on 27 minutes although before then Vardy had chased down Nicolas Pareja and blocked a routine clearance that ricocheted off for the Sevilla man and went out for a Leicester throw.
They loved that in the King Power because it was a reminder of what the team did best last season when the pitch was made intimidating and claustrophobic for opposing teams.
The goal began with that free-kick won by Vardy on the left side. Riyad Mahrez and Albrighton stood over it, offering left-foot and right-foot options.
It was Mahrez's left foot that swung the ball over in the end, away from the goalkeeper Sergio Rico and to Morgan at the back post where the ball more or less just struck the Leicester captain and went in.
Was there part of the celebration that was a nod to the Jamaica international's endorsement with a certain brand of rum? Certainly he mimed extending a telescope and looking into the crowd.
Leicester had the goal that their first-half performance had warranted and they grew in confidence. Vardy ran the right channel aggressively and pushed Sevilla back.
Leicester were leading the tie and the goal asked questions of their strategy, given the danger that Sevilla posed on the counter-attack.
Could Shakespeare's team afford to take a step back and try to absorb the pressure or did the occasion require them to push on for the second goal?
There were two changes from Sampaoli at half-time to try to re-energise a poor Sevilla side, including the former Manchester City striker Stevan Jovetic.
Spain international Sergio Escudero struck a sweet shot against the Leicester crossbar on 53 minutes and Wissam Ben Yedder made a big mess of the rebound.
It was moments such as these that make a team believe that they can prevail, and so just a minute later came the second goal.
From Mahrez's cross from the right there was a bad clearing header from Rami and Albrighton was permitted two touches of the ball before he picked his spot beautifully with his left foot.
There was not much about the Sevilla goalkeeper Rico that inspired confidence and a mistake followed to give Vardy a chance which he snatched at on 67 minutes.
Vardy had been forcing the issue all night but perhaps never more so than when he went nose to nose with Nasri on 73 minutes.
The Englishman saw his chance and threw himself backwards - and there was no getting away from the fact that he made the most of it he could. Both were booked, this being Nasri's second caution and the Frenchman was off.
More drama when the substitute Joaquin Correa played Vitolo in on 78 minutes and he went over the legs of Schmeichel as the goalkeeper came out.
It looked like Vitolo was already going over but there was nowhere else to go but into Schmeichel.
From the penalty spot N'Zonzi never looked composed and Schmeichel saved a spot-kick which would have taken Sevilla to extra-time.
In the closing stages it was Vardy who had the best chance but blazed over the bar. He punched himself in the face in frustration but that was the last setback of the night for Leicester.
Pep Guardiola has warned his Manchester City players they will be "killed" if they seek to defend their lead against a Monaco side who are "the best in the world at scoring goals" and that going for broke is the only way his team can win the Champions League this season.