Amad Diallo was the unlikely hero for Manchester United as they booked a spot in the FA Cup semi-finals.
The 21-year-old Ivorian star came on in the 85th minute to replace Raphael Varane and slotted home the eventual winner when Alejandro Garnacho broke free from Harvey Elliott's misplaced pass.
Manchester United fought back twice from losing positions, with goals from Marcus Rashford to level the scoring to 3-3 in extra time.
Diallo celebrated wildly as his goal in the 120th minute secured Manchester United's ticket to Wembley in the FA Cup semi-final.
His celebrations saw him sent off with a second yellow, though the youngster was in good spirits after his heroics in the closing moments.
The game was full of drama, as in true Man United v Liverpool style, the hosts went ahead early with a goal from Scott McTominay.
Goals from Alexis Mac Allister and Mohamed Salah put the visitors in front heading into the break, though Antony forced the game to extra time with a goal in the 87th minute.
Heading into the match, United were pitted as the underdogs to stand in Jurgen Klopp's way on their route to what could have been a historic quadruple in the German boss' final season.
Liverpool appeared to be on top, assuming control of the match, but Marcus Rashford and Amad Diallo secured the win for the hosts during an electric afternoon at Old Trafford.