The Reds conceded to a brilliant Said Benrahma strike early in the second half, after originally thinking the ball had been run out of play by Tomas Soucek.
But faced with the prospect of an early Emirates FA Cup exit, Erik ten Hag’s men found another gear, equalising through Nayef Aguerd's own goal before going on to win 3-1 inside 90 minutes, thanks to late goals from Alejandro Garnacho and Fred.
“It was tough to go down but we had the belief that we’d go on and win the game,” Maguire told MUTV after the final whistle.