Manchester United achieved safe passage to the next round of the Emirates FA Cup with a 2-1 victory over Leicester City.
The first half was a relatively even affair, punctured in the final few minutes when Bobby De Cordova-Reid nodded home a rebounded Wilfred Ndidi shot.
Alejandro Garnacho's substitution at half-time was the shot in the arm the Reds needed and, having his own effort blocked off the line seconds earlier, he was instrumental in creating the equaliser that was ultimately knocked home by Joshua Zirkzee.
Just as it looked like United were heading for another extra-time period in the FA Cup, Harry Maguire popped up at the back post to nod home a Bruno Fernandes header in the last few seconds of stoppage time.
FIRST HALF - DOWN AT THE BREAK
A key talking point from the off was the starting spot for wing-back Patrick Dorgu, signed from Lecce this January, with the assumption being he'd make his debut down the left flank. However, Amorim spoke pre-match of utilising players on the opposite wing and it appears he had the new man in mind when he said that, with the Dane beginning the match down the right side.
Dorgu got plenty of touches early on — important for building confidence in his home venue — in what was a relatively settled start to the match. The Foxes sent an early warning shot in the sixth minute through Jordan Ayew, well held by Onana, but the two teams were otherwise locked in a midfield battle for the opening quarter of an hour.
Amad and Dorgu, combining well on the right, both got shots off from around the edge of the box in quick succession but neither troubled Leicester goalkeeper Mads Hermansen.
The game dropped back into a quieter rhythm until the final 10 minutes of the first period, when Amad asked the next big question of Hermansen, delivering his corner kick right on top of the visitors' goalkeeper. The Dane almost spilled the ball on the line, but was able to gather it before one of Amorim's men could pounce.
The Reds were left to regret not punishing Hermansen’s dropped catch had found a way into the back of the net moments later when the Foxes took the lead.
Bilal El Khannouss entered United's penalty area on the left and pulled the ball back to Wilfred Ndidi in the centre. The Leicester captain’s shot was blocked by Onana, but Bobby De Cordova-Reid popped up in the scene to nod the opener in from point-blank range.
In the blink of an eye, Amorim's side were heading into the break with more work to do than they bargained for in the second half.
SECOND HALF - MAGIC MAGUIRE
Sensing the need to breathe some fresh life into the tie, Amorim turned to his bench to make a half-time substitution, replacing debutant Dorgu with Alejandro Garnacho, shifting Amad to wing-back in the process.
It injected some energy soon after the restart, with Rasmus Hojlund powerfully charging to the Leicester byline inside the first 60 seconds, but he was nudged off the ball at the crucial moment.
Garnacho's introduction on the left side added an extra bite and, just past the hour mark, almost a goal.
The Argentina international sprinted down the left side and faced up Hermansen, opting to chip the Danish goalkeeper. It came off, and the Old Trafford crowd rose in anticipation of a goal but, seemingly out of nowhere, defender Caleb Okoli managed to get enough contact on the line to send the ball crashing into the crossbar and away from goal.
Debates about whether the ball crossed the line would soon be rendered academic as minutes later Garnacho was approaching Leicester's goal again. This time he found Hojlund in the centre, whose improvised flick was blocked, but it didn't matter as substitute Joshua Zirkzee was in the right place at the right time to prod home the equaliser, the momentum clearly shifting in the Reds' favour.
The game was end-to-end at this point, with Garnacho looking consistently dangerous down the left and Noussair Mazraoui required at the other end to perfectly time a tackle as the last man to neutralise a Foxes break.
It looked like we were heading for extra-time when Bruno Fernandes put the ball down for a free-kick. United needed a hero, and he duly arrived in the form of Harry Maguire, arriving at the back post to nod home the all-important stoppage-time winner.
The Reds were heading to the next round of the FA Cup, and not for the first time in dramatic fashion at Old Trafford.
MATCH DETAILS
United: Onana; Yoro, Maguire, Mazraoui; Dorgu (Garnacho 46), Ugarte (Casemiro 90+4), Fernandes (c), Dalot; Amad, Mainoo (Zirkzee 64); Hojlund.
Substitutes not used: Graczyk, Lindelof, De Ligt, Heaven, Eriksen, Collyer.
Goals: Zirkzee 68, Maguire 90+3.
Booked: Ugarte.
Leicester City: Hermansen; Justin, Okoli, Faes, Thomas (Coulibaly 58); Ndidi (c) (Winks 58), Soumare; De Cordova-Reid (McAteer 73), El Khannouss; Ayew, Daka (Buonanotte 81).
Substitutes not used: Stolarczyk, Coady, Skipp, Mavididi, Monga.
Goals: De Cordova-Reid 42.