Leicester - Manchester United will spend Christmas 13 points behind Manchester City in the Premier League title race as Harry Maguire's dramatic late equaliser earned Leicester City a 2-2 draw on Saturday.
Juan Mata looked set to inspire a United victory as Jose Mourinho's side fought back from conceding Jamie Vardy's 50th Premier League goal on 27 minutes.
Mata had scored a superb free-kick on the hour-mark to fire United ahead at the King Power Stadium after a clever finish on 40 minutes had levelled the scores.
But four minutes into stoppage-time Maguire headed home a Marc Albrighton cross to leave United stunned and push Pep Guardiola's leaders another step towards the title.
After a bright start from United Leicester needed goalkeeper Kasper Schmeichel to come to their rescue after another clever United move.
It ended with Jesse Lingard's effort from the area deflecting off Christian Fuchs, forcing Schmeichel into a fine, reaction save high to his left.
United were making all of the early running and Schmeichel had to make another save, albeit a routine one, to stop a 20-yard effort from Paul Pogba.
In the 19th minute, Anthony Martial chased a ball into the left-hand corner for United and kept it in before crossing to the far post, where Romelu Lukaku tried an overhead kick that flew wide.
Leicester threatened briefly on 26 minutes but Riyad Mahrez fired straight at United goalkeeper David De Gea after neat work by Albrighton and Gray.
And a minute later the Foxes were ahead courtesy of a deadly counter-attack and some ragged United defending.
It was started by a superb, first-time pass by Wilfred Ndidi to put Mahrez one-on-one with Smalling and the Algerian kept his composure, waited for Vardy to arrive and rolled the ball into the striker, whose low finish gave De Gea no chance.
Mourinho's mood was not improved moments later when Pogba drilled a woeful effort from long range over the crossbar or when the same player sent an ambitious lob from the halfway line wide of goal.
But United were level five minutes before half-time in scruffy fashion when Leicester failed to clear a left-wing cross and Mata seized on the loose ball to squeeze a shot into the bottom corner.
Leicester should have taken the lead early in the second half after Mahrez found space to advance down the right.
He crossed towards the far post, where Fuchs had arrived, but the Austrian's powerful low drive was blocked by Victor Lindelof.
But moments later it was United's turn to go close as referee Jonathan Moss played a good advantage to allow Jesse Lingard to make a counter-attacking run.
He squared for Martial, who blazed over the crossbar when he should have tested Schmeichel.
It took just three minutes more for United to move ahead as Mata capped a fine game with his second goal.
Leicester fouled Martial a couple of yards outside the penalty area and Mata curled a left-footed free-kick over the wall and under the crossbar with Schmeichel flailing.
With 19 minutes remaining, United should have put the game to bed when Romelu Lukaku used his power to hold the ball up before producing a smart through-ball for Lingard.
But the youngster stroked his left-footed effort against the base of Schmeichel's left-hand post.
Leicester's task was made even harder, however, when Amartey was dismissed after just 17 minutes on the field.
He was booked twice in five minutes for fouls on Ashley Young and Marcus Rashford and duly received a red card.
Rashford should then have scored after more good work from Lukaku, but the striker delayed his shot and allowed Schmeichel to turn the ball away.
And United paid for wasting those chances when Albrighton crossed and Maguire headed home in the final seconds.