Southampton staged a stunning comeback from 3-0 down at Leicester with four goals in the last 30 minutes earning a 4-3 victory.
Leicester interim Andy King looked set for his first victory since taking charge after first-half goals from on-loan Manchester City youngster Divine Mukasa, Patson Daka and Abdul Fatawu.
But once substitute Ross Stewart had reduced the deficit, the hosts' brittle confidence was exposed with Jack Stephens, Ryan Manning and Shea Charles also pouncing to leave King's men without a win in six outings and put the home fans in mutinous mood.
Seven years after thrashing them 9-0 at St Mary's and only two after plundering five during Southampton's last trip to the King Power Stadium, City began the match with high hopes of clawing back three of the six points they were recently deducted by the EFL.
But, still searching for a permanent manager following Marti Cifuentes' departure and languishing perilously close to the relegation zone, the hosts are a very different beast to the one the visitors encountered here in April 2024.
Nevertheless, having seen Cameron Archer inexplicably turn Leo Scienza's cross over the bar from six yards out, City initially found themselves dreaming of another landslide win after netting in the ninth and 13th minutes.
Mukasa, making only his second appearance for King's side and first inside this ground, punished Archer for what was a woeful miss by drilling Daka's lay-off past Daniel Peretz.
Then, having created the chance his new team-mate converted, the Zambian doubled City's advantage after pouncing on Tom Fellows' misplaced backpass.
The former West Brom midfielder did not spot Daka before casually stroking the ball in the direction of Peretz. But, alert to his opponent's intentions, Daka seized possession and rounded the Israel international before finding the back of the net.
Southampton held an impromptu group discussion in the middle of the pitch after being breached twice during the opening period.
Their get-together did not have the desired effect, with Fatawu stretching City's lead still further in the 29th minute.
After controlling Mukasa's pass with a confident touch, his angled drive from distance left Peretz grasping at thin air.
Stephy Mavididi was inches away from heaping even more misery on Southampton, but could not twist a curling attempt inside the far post.
On one of the rare occasions Tonda Eckert's side did threaten, Caleb Okoli's lunging block prevented Archer's shot from reaching Asmir Begovic.
Stewart's delightful 61st-minute finish, which saw him guide home Scienza's pass, set the comeback in motion.
With eight minutes remaining, Stephens converted with his right foot following a defensive melee before Manning headed home from close range five minutes later, with Scienza again the provider.
Charles, who like Stewart and Manning had been introduced as Eckert rang the changes, thundered an unstoppable effort past Begovic deep into added time.
Leicester's caretaker boss Andy King:
"Let's not be naive about what has just happened there. The fans are fully justified to react the way they did at the end.
"I was very strong on the point at half-time that the game hadn't been won. I was pleased with the first half but it's certainly not a positive. There are no positives to take because of the second half. None at all.
"I can't explain what happened. I have spoken to the players and there is a sense of anger but I won't elaborate on that until I've had time to reflect more.
"I have had a conversation with the lads in the dressing room and it's right that they know my feelings on what happened."
Southampton head coach Tonda Eckert:
"At half-time, we reset. I asked the players to make a decision and that was if they wanted to have a proper go. In fairness, they had already made that decision for themselves.
"I didn't want to do too much talking to the players about structure. I wanted to leave that to the staff.
"For me, it was more about dealing with the emotions. There's a lot flying around.
"I give full compliments to the players. It is tough to find the right words because there are so many thoughts still buzzing around.
"I don't have an explanation for what happened during the first half. We were just a step late to everything and were poor in possession and out of possession. But we bounced back. It was a crazy night."
