No offense but it's in competitions like these that we tend to see the best of Man UTD. Grimsby may be a good team in their division but I doubt they would be able to withstand the pressure of a top side like the Red Devils. I can't predict the correct score but I know that Man UTD would win by a huge margin.
Aren't we always pay attention with Manchester United in any competition?

Grimsby Town isn't even a good team at all, they're mediocre in League Two. The gap level between Manchester United and Grimsby Town is big, even though Manchester United didn't win the last two match, but their performance weren't awful. First match they were treated unfair, the second match Bruno unlucky to miss penalty.
Manchester United should able to win with two goals difference.
This is a match Manchester needs right now, so they would use it yo build a winning mentality in the team. I think Ruben Amorim knows this as well so he won’t joke around getting result in this match. For sure you can’t take away Manchester United performance from the last the games they’ve played, in the arsenal match I think they deserve at least a point from that match, and in the Fulham match maybe, just maybe if Fernandez had converted that penalty the outcome of the match would have been different.
I expect nothing less than 3 goals up from Manchester United in this match, this is a team who is playing in league 2, so it should be more like a forfeit match for them. Well this is football and you can expect the worse but I’m confident Manchester United will blow away Grimsby in this fixture.