Boss Brendan Rodgers took the blame after Leicester crashed out of the FA Cup.
Tyrhys Dolan and Sammie Szmodics capitalised on awful defending to earn Blackburn a 2-1 win as they reached a first FA Cup quarter-final for eight years.
Kelechi Iheanacho grabbed a second-half consolation but the error-prone Foxes got what they deserved against the Championship side.
Rodgers, who guided Leicester to a first FA Cup triumph in 2021, made six changes and insisted he should be the one in the firing line.
He said: “If there’s anyone to blame it’s me. I made the changes and sadly it didn’t work.
“We brought four players into the starting line up who won the FA Cup a couple of seasons ago so the team should be strong enough and good enough.
“The FA Cup was a chance to get to a quarter-final, we were playing against a Championship team at home but they were better than us and we have to worry about that.
“They were the better team. We presented a couple of goals, giving the ball away cheaply. Then you are chasing it and 2-0 is an easy scoreline to go freely. We showed spirit and we showed drive then but you have to show that when it’s 0-0.
“It’s just consistency, it’s mentality, ambition and drive to succeed. That’s been too up and down for us. It doesn’t help when you continually present chances. We just didn’t perform well, it’s as simple as that.”
Tete and Dennis Praet went close early but Leicester quickly regressed and their shocking passing, especially in defence, gifted Blackburn chances.
Szmodics and Dolan both went close – with Daniel Iversen’s fine save denying Dolan – after errors from Daniel Amartey before Blackburn went ahead after 33 minutes.
Again it was Amartey who presented the ball to Dolan and the former Manchester City youngster seized on the chance, darting towards the area and finishing past Iversen from 20 yards.
It got worse for the Foxes seven minutes after the break when Szmodics bundled his way past Amartey and Ricardo Pereira for his low finish to roll past Iversen.
The goal came after Sam Gallagher robbed Luke Thomas and Leicester had already been given a warning after Ryan Hedges shot wide – following Boubakary Soumare losing possession on the edge of the box.
Iversen denied Szmodics as Blackburn went for the kill but Iheanacho grabbed a goal back with 23 minutes left when he converted Harvey Barnes’ cross.
The Foxes tried to save themselves with Aynsley Pears denying Iheanacho and Amartey’s header hitting the post.
Blackburn boss Jon Dahl Tomasson said: “It was an unbelievable night for the club. The performance and result was well deserved. I asked the players to be brave on the ball.
“They followed the game plan perfectly. We were extremely brave, we were creating chances and out of possession we were extremely intense.
“We should have been out of sight before it got a bit nervous but the lads showed a lot of spirit, fighting when it was needed. The players have written another chapter in our great history.
“We are under construction. We have been inconsistent but in 2023 we have been consistent. The lads have done an excellent job.
“Now we are in the last eight in the greatest cup in the world. This cup is one of the only ones where it really is alive. We take the cup very seriously.”
