Leicester manager Craig Shakespeare insists the Foxes can win the Champions League.
They host Sevilla in the last 16 on Tuesday, trailing 2-1 from last month's first leg, in Shakespeare's first game as full-time manager.
Shakespeare won his first two matches in charge - before Sunday's confirmation he would be boss until the end of the season - following Claudio Ranieri's February sacking.
A 1-0 win at the King Power Stadium would send the Foxes into the last eight on away goals and, after last season's shock 5,000-1 Premier League triumph, Shakespeare said Leicester must believe they can win the competition.
"Why not? We are in it, we have to try to be competitive in every game," said the 53-year-old, who was Ranieri's assistant. "For me there is no free game in football, you have to try to win every game you go in to and show that determination and competitiveness and we need to show that in abundance tomorrow night.
"We know the importance of getting that goal. It is going to be a huge task but hopefully with the crowd - and we make a good atmosphere here - we can go through."
Jamie Vardy's away goal at the Ramon Sanchez Pizjuan Stadium gave the Foxes hope after Kasper Schmeichel made a number of saves, including from Joaquin Correa's first-half penalty, to keep them in the tie.
Ranieri was dismissed just 24 hours after the defeat in Spain but Shakespeare believes Vardy's strike gives the tie a different complexion.
He said: "Evan after the first game we knew by getting the away goal we had given ourselves a great opportunity.
"The atmosphere will be electric and I'm expecting the team to take momentum from the two results (wins over Liverpool and Hull) and the confidence gained from that and really play on the front foot.
"That is not to say we will be open as we know Sevilla have world-class players but it makes for an interesting game because of their away goal.
"I'm quite calm and collected. Hopefully I'll stay calm so the players aren't over-emotional. Of course I'll be excited. We have to compete for the 90 minutes or extra-time. I understand the massive challenges ahead, no more so than tomorrow."
Nampalys Mendy is out with a knee injury, although Shakespeare is hopeful he will be fit for Saturday's Premier League trip to West Ham, while Robert Huth and Islam Slimani are a booking away from a ban.
The Foxes have also practised penalties in case of a shoot out at the King Power Stadium.
"We have, we are trying to leave no stone unturned - and by the way they were good, hopefully we can carry that on," Shakespeare added.
Danny Drinkwater is expected to start in midfield and he backed Sunday's appointment of Shakespeare, who was also assistant to former boss Nigel Pearson.
The England international said: "On behalf of all the players I think all of us would like to see him get the job long term.
"It's a great appointment. It's a good fit. We haven't got much time to turn things around but there's no better person for the job.
"I don't think it's changed an awful lot. He needs to take control more as manager and any changes he's made have been positive for the players.
"He's been a pleasure to work with as manager - but he's taken different roles as a coach. He helps us enjoy the football. It's not only for the players and manager but one of the biggest games in the club's history."