Leicester boss Craig Shakespeare believes the Premier League winners can spring further surprises after progressing to the Champions League quarter-finals.
Wes Morgan and Marc Albrighton were on target as the Foxes overturned a 2-1 first-leg deficit to advance 3-2 at the expense of Sevilla.
Bayern Munich, Barcelona, Juventus and Borussia Dortmund are already in the last eight, while Manchester City could join the Foxes with victory at Monaco on Wednesday night.
"We might just be the surprise team," Shakespeare said.
"We know there's going to be some terrific teams, as there were in the previous round.
"We have to be delighted with the performance and knocking Seville out. Their record in Europe is there for everyone to see.
"We're in there on merit. Make no mistake about that."
Morgan said on BT Sport 2: "Incredible, I can't quite believe it. We're newcomers in the Champions League, we didn't expect to get this far and here we are.
"I'm not sure this is ever going to happen again, but we did it.
"We did it and we proved a lot of people wrong. It was a big game for us and a big night for everyone involved with Leicester and we've pulled off the impossible again."
It was Shakespeare's first game as a full-time boss after his appointment until the end of the season was confirmed on Sunday.
And he became the third English manager to make the last eight after Harry Redknapp and Sir Bobby Robson.
Claudio Ranieri, who led the 5000-1 outsiders to the Premier League title last season, was sacked after the first-leg loss in Spain, but Shakespeare paid tribute to his predecessor.
"Claudio will always been fondly remembered by everyone at this football club for what he achieved and helped us achieve," he added.
"The performance in the first leg when Claudio was in charge, that gave us the springboard for the result tonight."
Leicester have won all three of Shakespeare's matches in charge - the Sevilla win followed successes against Liverpool and Hull - despite him sticking with the same team which delivered the unexpected title under Ranieri.
He added: "It was very, very important to get on a winning streak. When you lose, players will lose confidence.
"We needed to get back to winning ways as soon as possible."
Shakespeare lauded his players on a night few in Leicester will ever forget.
"It will be memorable for everyone at the football club," he added.
"It has to stand up there with all the achievements, because of the quality of the opposition.
"It is only over two legs and when you win the league it's over a lot more games."
There was controversy on the night as Samir Nasri was sent off for a headbutt on Jamie Vardy, who reacted dramatically.
Shakespeare said he was yet to see a replay, while Sevilla boss Jorge Sampaoli pointed to the incident as a pivotal moment.
Sampaoli, who was sent from the touchline late in the game, also rued his side's second penalty denial of the tie, as Kasper Schmeichel saved from Steven N'Zonzi.
"It became a really tall order after missing the penalty," Sampaoli said.
"We never stopped trying to look for opportunities to score and to get back into the game.
"It's too early to talk about failure. I'm very proud of my team. Even though we played with 10 men, we never stopped trying.
"We were superior in terms of possession in both games. We tried our hearts out.
"The fault lies at the feet of the manager, but I'm really proud of the effort my boys put in tonight."