Claudio Ranieri shouldered full responsibility for Leicester's 3-0 Premier League capitulation at Southampton, then admitted the Foxes have dropped into a relegation dogfight.
Leicester equalled the worst record after 22 games of any top-flight defending champions in England, sitting alongside Ipswich's struggles from the 1962-63 campaign.
Ipswich avoided the drop by finishing 17th that term, but Ranieri has accepted his Leicester side are now fighting for their Premier League future.
James Ward-Prowse, Jay Rodriguez and Dusan Tadic condemned Leicester to their 11th defeat in 22 league matches on the south coast, leaving boss Ranieri to admit he should not have tinkered with his side's tactics.
Asked if Leicester are now in a relegation battle, Ranieri replied: "Yes of course, and it's for this reason that I've wanted 40 points all along from the start of the season.
"I said this from the beginning, and I maintain the focus on 40 points, it's important to achieve that as soon as possible."
Leicester's woeful south coast showing raised real fears the Foxes could become the first top-flight champions to suffer relegation since Manchester City in 1938.
Ranieri moved to ease criticism away from his players however, insisting he had been at fault for shifting their tactics away from the 4-4-2 formation that drove last term's title heroics.
"I tried to help my players in the last two matches. I changed our normal shape against Chelsea, to three at the back and today I played with a diamond, and this led to some misunderstanding," said Ranieri.
"My players are used to playing 4-4-2, or 4-2-3-1, so for this reason I have made mistakes and it's my fault in the last two matches. It's one thing trying it in training and another entirely on the pitch.
"I changed it because it wasn't so good and I wanted to help them. But my idea to help them was wrong, it's much better to continue with what they recognise, and then we can be better."
Southampton's cruise-control victory was tempered only by an ankle injury to talisman centre back Virgil van Dijk.
The captain hobbled off in the second half to become an immediate doubt for Wednesday's EFL Cup semi-final second leg at Liverpool.
Now that Jose Fonte has left for West Ham in an £8m deal, England Under-21 international Jack Stephens could start that cup clash at Anfield.
"Virgil took a big kick and we will see if we can recover him for this game," said manager Claude Puel.
"I hope we can have Virgil of course because he is our captain and he's an important player. "He could not continue the game. We will see for the next games, I don't know if he can recover.
"For Jack (Stephens) it's been an opportunity to play and show all his qualities."
SOUTHAMPTON: Forster, Cedric, Yoshida, van Dijk (Stephens, 55 mins), Bertrand, Hojberg (Clasie, 73 mins), Romeu, Ward-Prowse, Redmond, Rodriguez (Long, 79 mins), Tadic. Unused subs: Taylor, Martina, McQueen, Sims.
Leicester: Schmeichel, Simpson, Morgan, Huth, Fuchs, Ndidi, Drinkwater, Mendy (Albrighton, 46 mins), Okazaki (Musa, 63 mins), Gray, Vardy. Unused subs: Zieler, Chilwell, King, Kapustka, Benalouane.