However, strikes from David Nugent and Esteban Cambiasso drew Leicester level, before Jamie Vardy and Leonardo Ulloa secured all three points for the home side in the closing stages, while United also lost defender Tyler Blackett to a red card.
Here, Sports Mole has looked back over the contest to determine if the result was a fair one.
On target: 5
On target: 5
Was the result fair?
When Herrera put United 3-1 up, there only looked to be one winner. However, albeit with some good fortune, Leicester rallied and got themselves back into the game. On the balance of play, a draw may have been the fairest outcome, but when you defend as United did, you deserve to punished and the home side duly obliged.
After conceding two early goals, Leicester controlled most of the first half, without causing too many problems. It was a similar story in the second half, but the goals arrived. Nigel Pearson is bound to be delighted with the desire that his side showed at 3-1 down because it would have been very easy for them to accept their fate. They created numerous chances against a porous defence, but what will also have pleased Pearson is the fact that they limited United's opportunities in the closing stages.
Man United's performance
Louis van Gaal will have seen a lot of things during his managerial career, but there won't have been many matches that have shocked him like this one. At 3-1 up, his side should have shut the game out, but defensively they don't have that capability and that was highlighted badly today. United supporters may well point to a poor refereeing decision that allowed Leicester back into the contest, but that was no excuse for their side to hit the self-destruct button. It goes to show that you can have all the attacking talent in the world, but if you cannot defend, you will still have problems.
Sports Mole's man of the match
Jamie Vardy: The attacker was restored to the team and he certainly made the most of that opportunity. In what was a lively showing, Vardy assisted one goal, won both penalties and also scored the goal that put his team 4-3 in front with a really composed finish. It's probably safe to say that he will keep his place next time out.
The United defence can take this award for doing a disappearing act as Leicester scored their fourth goal. The likes of Marcos Rojo, Chris Smalling and Rafael da Silva were nowhere to be seen as Vardy fired in. Had United been trailing, pushing up that far would have been understandable, but they were level at three goals apiece.
Mark Clattenburg, to put it bluntly, had a shocker. In the first half he bizarrely awarded United a corner when Di Maria's shot had clearly not struck any Leicester players, but worse was to come. In Leicester's first penalty incident, Vardy clearly pushed Rafael over, but no foul was awarded. Then, when the two players collided inside the area with minimal contact moments later, Clattenburg didn't hesitate in pointing to the spot.
Leicester: The Foxes are on the road next Saturday afternoon when they travel to London to face Crystal Palace at Selhurst Park.
Man United: As for United, they return to the home comforts of Old Trafford with the visit of West Ham United.