Both sides were looking to return from the international break with a bang after recent struggles, with the visitors higher in the Premier League but under more intense scrutiny.
That focus will only increase after Leicester won 4-2 at a rocking King Power Stadium, where Jamie Vardy and substitute Patson Daka scored late to condemn United to a first away league defeat since January 2020.
The end of that 29-match unbeaten run on the road came on a wild afternoon against the Foxes, who cancelled out Mason Greenwood’s stunner with a similarly impressive effort through Youri Tielemans.
Ex-Leicester defender Harry Maguire was at fault for the leveller and David De Gea had to produce some keys saves in the second half, before Caglar Soyuncu turned in what looked to be a late winner.
But there was still plenty of drama. Substitute Marcus Rashford – making his first appearance since the Euro 2020 final – levelled for United, only for Leicester to score straight from the restart through Vardy.
Daka turned home from a set-piece in stoppage time to add gloss to the scoreline as Brendan Rodgers’ side celebrated a superb victory.
An impressive atmosphere greeted the sides at the King Power Stadium, where Maguire – who was constantly jeered – was given a glimpse of what was to come on his return from a calf injury just six minutes in.
Paul Pogba lost the ball and Kelechi Iheanacho roared past the United captain, who got back to cut out a cross with Vardy lurking.
James Maddison produced a nice flick in that move and fired at De Gea from an acute angle as the Foxes continued strongly against the sloppy visitors.
But United boast individual quality that can get them out of difficult situations and Greenwood did just that in the 19th minute.
Having ended a fine run with a poor finish shortly before, this time the forward cut inside and rifled a left-footed laser that flew in off the post from 20 yards.
It was a gut punch that Leicester rallied from impressively.
Ricardo Pereira’s volleyed cross-shot flashed just across the face of goal and, after Cristiano Ronaldo saw a strike saved at the other end, Rodgers’ Foxes levelled in outstanding fashion.
United tried to play out from the back and dilly-dallying Maguire was tackled by Iheanacho, who cut back for Tielemans to hit a sublime lofted effort into the left-hand corner in the 31st minute.
There was a fantastic tempo to the match and Iheanacho dragged narrowly wide as half time approached, with Vardy just unable to get a telling touch at the end of a stoppage-time set-piece routine.
Iheanacho had an early effort saved and Greenwood twice missed the target during an open start to the second period, with Victor Lindelof booked for an ugly mistimed challenge on Vardy.
Nemanja Matic went close to scoring the third Filbert Way stunner of the day when lashing over from distance, with Kasper Schmeichel denying Greenwood from close range unaware offside would be called.
Tielemans and Bruno Fernandes missed the target after Rashford was brought on to add fresh impetus to the United attack.
But Leicester had grown in confidence and De Gea was forced to tip a Tielemans effort onto the post. Vardy was celebrating thinking it was in.
The United goalkeeper denied Daka with his legs soon after and stopped the substitute again from a corner, only for the ball to ricochet into the path of Soyuncu to turn home in the 78th minute.
Rashford and Ronaldo failed to combine for a goal shortly before that, but the former did find a goal four minutes after Leicester took the lead.
Lindelof fired a superb ball over the top and the substitute kept his composure before lashing past Schmeichel.
But this was to be Leicester’s day and they scored straight from the kick-off, with sub Ayoze Perez cutting back for Vardy to fire home.
Pereira flashed wide as Leicester threatened a fourth, which arrived in stoppage time as a free-kick was flicked into the path of Daka to turn home.