The Red Devils saw their long unbeaten Premier League away streak ended at 29 matches in the East Midlands after a flurry of dramatic late goals.
An entertaining contest was finely-poised at 1-1 heading into the final 13 minutes after Mason Greenwood and Youri Tielemans had earlier traded memorable first-half goals.
Centre-back Caglar Soyuncu then put Leicester in front, with substitute Marcus Rashford levelling for United on his eagerly-awaited return from shoulder surgery.
However, Jamie Vardy struck again straightaway, with a rousing victory for the Foxes then wrapped up in stoppage time by Patson Daka.
The result heaps more scrutiny on Solskjaer ahead of an extremely tough run of fixtures for United.
Follow Leicester vs Manchester United reaction LIVE with Standard Sport’s blog below!
Leicester vs Manchester United highlights
GOAL! Substitute Daka makes it four in stoppage time
GOAL! Vardy quickly restores Leicester’s lead
GOAL! Rashford scores on return from injury
GOAL! Soyuncu puts Foxes in front
GOAL! Tielemans nets stunner after Maguire error
GOAL! Greenwood scores with rocket
16:56 , George Flood
Leicester 4-2 Manchester United
GOAL! Leicester 4-2 Manchester United | Patson Daka 91'
16:51 , George Flood
91 mins: Game over!
United can’t clear a Leicester corner in stoppage time and substitute Daka is there to finish at the back post.
He’s the first Zambian to score a Premier League goal.
More pressure mounts on Ole Gunnar Solskjaer.
16:51 , George Flood
Leicester brought on Vestergaard for Evans and Pogba was booked for fouling Daka.
McTominay and Lingard came on a little earlier for United, with Matic and Greenwood off.
GOAL! Leicester 3-2 Manchester United | Jamie Vardy 83'
16:45 , George Flood
83 mins: What is going on?!
A superb finish from Vardy straight from the restart after he was teed up by Perez.
A ridiculous game!
GOAL! Leicester 2-2 Manchester United | Marcus Rashford 82'
16:45 , George Flood
82 mins: He’s back!
Substitute Rashford thunders past Schmeichel after collecting Lindelof’s pass.
All square once again. What a finish we have in store...
GOAL! Leicester 2-1 Manchester United | Caglar Soyuncu 79'
16:40 , George Flood
79 mins: Leicester are in front!
Daka’s strike following a corner is deflected by Perez and Soyuncu fires in ahead of Maguire.
16:39 , George Flood
77 mins: Ronaldo and Rashford lead a United break and the former is denied by Schmeichel.
However, the offside flag is up.
Patson Daka on for Leicester.
16:38 , George Flood
75 mins: What a save!
Tielemans catches Matic in possession, fights past Pogba and runs at Maguire.
He then provides a decent shot that is somehow pushed onto the post by a diving De Gea.
A fine, fine stop.
16:36 , George Flood
73 mins: Ayoze Perez for Maddison is Rodgers’ first change of the afternoon.
16:34 , George Flood
70 mins: A break in play now as Amartey receives some treatment after Ronaldo had threatened.
Some autumn sunshine just covering one quarter of the pitch could cause some problems for this Leicester defence.
16:30 , George Flood
68 mins: Rashford is involved in United’s next attack that ends on a disappointing note as Fernandes fails to find the target with a hopeful strike.
16:28 , George Flood
65 mins: Now Rashford does come on. Sancho the man to make way.
That’s a terrible clearance from Lindelof after a surging run from Maddison and Tielemans fires the loose ball over the top.
16:27 , George Flood
64 mins: Fernandes runs in behind the Leicester defence and causes panic with a sweet outside-of-the-boot cross towards Greenwood and Ronaldo.
Schmeichel ends up making a decent close-range save to deny Greenwood, but the offside flag is then raised.
16:24 , George Flood
61 mins: That’s a really poor corner from Maddison and United break, but Leicester manage to avert any real danger.
Momentum swinging back and forth here. Rashford still waiting to enter the fray over on the touchline.
16:22 , George Flood
60 mins: Rashford is preparing to come on for Manchester United now as he makes his return from shoulder surgery.
Important defending from Lindelof at the front post to turn a dangerous cross behind.
16:20 , George Flood
55 mins: A superb tempo to this contest now as Tielemans rifles over from the edge of the United box.
A brilliantly-poised game with the crowd well up for it.
16:16 , George Flood
53 mins: Maddison’s initial effort strikes the wall before he powers the rebound well over the crossbar.
At the other end, Matic unleashes a wonderful left-footed half-volley that has Schmeichel worried and at full stretch.
However, it whistles just over the top. What another outstanding goal that would have been.
16:14 , George Flood
52 mins: Lindelof wipes out the speedy Vardy and is the first player to have his name taken by referee Craig Pawson.
This free-kick is definitely within range for Maddison...
16:12 , George Flood
50 mins: Ronaldo does well to pick out Greenwood, who is once again shown onto his left foot.
His finish is rather wild again, but Leicester are playing a very risky game with their approach to defending the talented 20-year-old.
One of these is going to nestle in the top corner, sooner rather than later.
16:10 , George Flood
48 mins: At the other end, Greenwood cuts across Soyuncu before ballooning a tricky shot into the stands.
A lively start to this second period at a sunny King Power.
16:09 , George Flood
46 mins: A very early second-half chance for Leicester as their high-intensity pressing catches United out once more and Iheanacho bursts forward before his strike is at a nice height for De Gea, who saves comfortably.
16:07 , George Flood
Back underway at the King Power.
No changes from either manager.
16:00 , George Flood
23 - Kelechi Iheanacho has been directly involved in 23 goals in his last 26 games for Leicester in all competitions, scoring 17 and making six assists. Productive.
— OptaJoe (@OptaJoe) October 16, 2021
15:52 , George Flood
Leicester 1-1 Manchester United
15:51 , George Flood
48 mins: Maddison lines up a late free-kick after being tripped by Fernandes.
Leicester pull off a dangerous training-ground move and Lindelof’s slight touch on the cross just does enough to force Vardy into touching wide from close range.
That was very close. The half-time whistle immediately sounds as Vardy appeals for a corner.
15:49 , George Flood
46 mins: Into three minutes of stoppage time at the end of this first half.
A rare miskick from Ronaldo inside the Leicester box after a tidy one-two with Shaw, with the Portuguese then trying an acrobatic overhead kick following a cross from compatriot Fernandes.
It’s brave defending from another Portugal international, Ricardo Pereira, who sticks his head in the way and earns a pressure-relieving free-kick.
15:46 , George Flood
43 mins: United struggling to find any decent end product since that brilliant Greenwood strike as their latest attack breaks down with a bit of a whimper.
Half-time beckoning at the King Power as Tielemans tries to pick out Castagne with a curling cross to the back post, but it drifts wide.
15:42 , George Flood
39 mins: De Gea breathes a sigh of relief as Iheanacho’s dangerous low strike flashes narrowly wide of the far post after Maddison and Tielemans combine nicely in midfield.
Iheanacho has given the returning Maguire a bit of a torrid time thus far this afternoon.
15:38 , George Flood
34 mins: Leicester almost get Vardy in behind before Maddison is caught by an accidental stray elbow from Matic.
He’ll need some treatment.
GOAL! Leicester 1-1 Manchester United | Youri Tielemans 31'
15:33 , George Flood
31 mins: Another great goal, but it’s a bad mistake from Maguire against his former club.
He’s caught in possession by Iheanacho, who tees up Tielemans for a sublime, audacious first-time effort that loops over De Gea and in.
Two cracking goals of the highest order and it’s all square again.
15:33 , George Flood
29 mins: A strong save from Schmeichel denies Ronaldo after the Portuguese links up well with Sancho down the United left and they somehow keep the ball in play.
Solskjaer’s side quickly come again and a low strike from Pogba goes well wide, with Leicester very aggrieved at the surprise award of a corner.
15:29 , George Flood
27 mins: Leicester come close to an equaliser as Ricardo Pereira cushions a dangerous ball across the box and comes within a whisker of squeezing it in at the back post.
I think he was trying to pick out Vardy, but that was mightily close.
15:27 , George Flood
24 mins: A vital defensive header there as United get back on the front foot and Fernandes delivers a menacing corner into the six-yard box.
15:24 , George Flood
22 mins: Leicester try to hit back quickly, but Iheanacho’s effort is blocked and a tame follow-up strike from Vardy is easily gathered by De Gea.
GOAL! Leicester 0-1 Manchester United | Mason Greenwood 19'
15:21 , George Flood
19 mins: What an incredible strike!
After patient United build-up, Greenwood comes in from the right flank, drifts across Castagne before thundering an unstoppable effort into the top corner with Schemichel helpless.
A fantastic goal. Wow.
15:19 , George Flood
16 mins: More Leicester pressure, but United work a corner and Bruno Fernandes’ deep delivery is headed high and wide by Pogba.
Tielemans marking Maguire there is a mismatch that is surely asking for trouble from a Leicester perspective.
15:16 , George Flood
12 mins: A sight of goal for United after dealing with that early Leicester pressure as Greenwood combines well with Ronaldo down the right flank, gets across Evans and then shapes to shoot but bends an effort straight into the grasp of Schmeichel.
15:13 , George Flood
8 mins: Promising stuff from Leicester as Tielemans looks to release Iheanacho with a brilliant pass into the right channel, but Lindelof is there to see it off.
Lindelof also slices clear as the Foxes keep the attack alive and try to pick out Vardy with a slightly overhit cross to the back post.
United doing a lot of early defending at the King Power.
15:09 , George Flood
6 mins: Maguire is beaten all ends up during a superb run from Iheanacho, but gets back to make a crucial intervention as Tielemans plays a dangerous square ball into the six-yard box looking for Vardy.
A really promising attack from Leicester.
15:07 , George Flood
4 mins: Leicester can’t fashion a chance after Maddison is brought down cynically by Matic.
United then come forward as Sancho looks to play in Ronaldo, but Evans does enough and Schmeichel can collect the through ball.
15:04 , George Flood
2 mins: Maguire is thrust straight into the action on his former ground, with Leicester pressing high and with real intensity during these early stages.
Vardy and Iheanacho have Maguire boxed in near the byline as United struggle to play out from the back.
15:01 , George Flood
Off and running in the East Midlands!
Which of these sides will get back on track this afternoon?
14:58 , George Flood
Here come the teams at the King Power Stadium.
We’ll be underway very shortly!
Solskjaer: Martial not fit after international duty
14:50 , George Flood
Solskjaer has explained the reason for Martial’s absence from the United squad during a pre-match chat with MUTV.
"He’s come back from France [duty] not fit so he’s not trained all week," he said.
"Hopefully we can have him back soon."
Standard Sport prediction
14:40 , George Flood
Jamie Vardy has been in good form of late despite Leicester’s struggles and refreshed after the international break, he can take advantage of United’s defensive concerns to earn a share of the spoils.
Leicester 2-2 Man United
Leicester team news: Five changes, Evans starts
14:33 , George Flood
Leicester, meanwhile, make five changes to the team that threw away a two-goal lead at Crystal Palace before the international break.
Jonny Evans is fit to play against his former club, so Jannik Vestergaard makes way, while Daniel Amartey, Ricardo Pereira, Boubakary Soumare and James Maddison replace Ryan Betrand, Ademola Lookman, Hamza Choudhury and Harvey Barnes.
Man United team news: Maguire starts
14:25 , George Flood
So the big team news from a Manchester United perspective is that Harry Maguire - who has missed the last two matches with a calf injury and only returned to working on the grass late in the week - is deemed fit enough to start against his former club this afternoon.
Fellow centre-half Victor Lindelof deputises for Raphael Varane, who will miss the next few weeks with a groin injury suffered while on duty with France.
Cristiano Ronaldo leads the attack after his record hat-trick for Portugal against Luxembourg, while there is also a start for Jadon Sancho.
There’s no Anthony Martial and Fred and Edinson Cavani are both unavailable after international duty in South America, with Nemanja Matic coming into midfield alongside Paul Pogba, with Scott McTominay among the subs.
Manchester United team
14:02 , George Flood
De Gea, Wan Bissaka, Lindelof, Maguire, Shaw, Pogba, Matic, Greenwood, Bruno Fernandes, Sancho, Ronaldo
Subs: Bailly, Mata, Rashford, Lingard, Dalot, Henderson, Alex Telles, Van de Beek, McTominay
14:01 , George Flood
Schmeichel, Amartey, Evans, Soyuncu, Ricardo Pereira, Tielemans, Soumare, Castagne, Maddison, Iheanacho, Vardy
Subs: Bertrand, Barnes, Albrighton, Ward, Perez, Choudhury, Vestergaard, Daka, Lookman
13:51 , Giuseppe Muro
Team news is coming in 10 minutes...
Head to head history and results
13:48 , Giuseppe Muro
Leicester wins: 3
Manchester United wins: 19
13:40 , Giuseppe Muro
Leicester defender Jonny Evans, who has been battling a foot injury and recent illness, is under consideration for his first league start since April.
Jannik Vestergaard has an unspecified fitness issue and will be assessed.
Early team news
13:30 , Giuseppe Muro
United are facing injury problems at centre-back with both Harry Maguire and Raphael Varane ruled out, so Victor Lindelof and Eric Bailly are expected to start.
Maguire is still out with a calf injury and Varane is set to be out for a few weeks with the groin injury he suffered while playing for France over the international break.
Marcus Rashford is fit again after recovering from shoulder surgery. Cristiano Ronaldo will lead the line after his stunning hat-trick for Portugal.
United are without Fred and Edinson Cavani, who were involved in a South American World Cup qualifier in the early hours of Friday morning.
How to watch
13:20 , George Flood
Today’s match will not be broadcast live on TV in the UK.
However, you can catch highlights on Match of the Day on BBC One from 10:30pm.
13:11 , George Flood
It feels like a big afternoon for Manchester United.
Their form dipped just prior to the break, with a 1-0 home defeat to Aston Villa followed by a 1-1 draw with Everton at Old Trafford to raise fresh questions about Ole Gunnar Solskjaer’s management.
United will be desperate to return to winning ways in the Premier League.
Leicester, meanwhile, will be hoping that the international break can prove a turning point, with Brendan Rodgers’ side so far having failed to match the highs of last season.
Follow live coverage of the clash at the King Power Stadium, with kick-off at 3pm BST.
13:01 , Giuseppe Muro
Hello and welcome to Standard Sport’s LIVE coverage of Leicester v Manchester United in the Premier League.
We’ll have all the team news and build-up ahead of a 3pm kick-off...