United, trailing 2-0 with just 15 minutes left, fought back to level 2-2 and force a shootout. But the drama ended in heartbreak as Grimsby edged them out 12-11 on spot-kicks.

The upset has drawn comparisons with other famous moments in United’s cup history, including York City’s 3-0 win at Old Trafford three decades ago.

Grimsby’s triumph is already being hailed as one of the most memorable giant-killings in English domestic cup football.