The Premier League outfit have made a remarkable progression to the last eight and on Tuesday face a side who have thrived on adversity to compete in two Champions League finals in the last three years, having made it to four successive quarter-finals.
Leicester were outclassed for large parts of the first leg at a fervent Vicente Calderon Stadium but, crucially, return to the King Power Stadium on Tuesday with their storied opponents well in their sights after Antoine Griezmann's solitary goal.
"I think they are betting everything on the second leg," Atletico's charismatic manager Diego Simeone told reporters after a tough first encounter with the Midlands side.
"It was a hard-fought match. It's a good win for us but the second leg will be difficult. It's all still to play for.
"As for the second leg, we anticipate a fantastic English atmosphere. The tie is still 50/50. Nobody sees us already in the semi-final."
In the last round, Craig Shakespeare's Leicester side overcame a similar 2-1 deficit against Sevilla, winning 2-0 at home in the return to set up the Atletico showdown.
Once relative Champions League unknowns, however, Atletico are now true European giants and will provide the sternest test yet of Leicester's fairytale continental adventure.
MORE OPEN
"We know we have to be more open because we need a goal and one of Atletico's plusses is their ability on the counter-attack," Shakespeare told reporters after the defeat in Madrid.
"But we are still alive and we want to stay in the competition. I have seen enough throughout the squad. We know what we are about at the King Power and know what we need to do.
"Atletico are a very good team, their work ethic is exceptional. We are aware of that, but we are still in this tie.
"We know it is a going to be a very difficult return match, but we have very good record at the King Power."
Atletico welcome back striker Kevin Gameiro, who missed the first leg with hamstring problems, to the squad but are without midfielder Tiago, who returned from injury as a late substitute in Saturday's 3-0 Liga win over Osasuna but has been left out.
Atletico's Croatia defender Sime Vrsaljko and Argentina midfielder Augusto Fernandez are also missing through injury.
English champions Leicester, meanwhile, could be without several key defenders through injury and suspension.
Captain Wes Morgan has not played since the return leg with Sevilla and is doubtful, Robert Huth is suspended while Yohan Benalouane limped out of Saturday's 2-2 draw at Crystal Palace.
