Newcastle lost two games in a row prior to the international break
The Magpies suffered disappointing defeats against Burnley and Bournemouth prior to the international break but will be determined to cause an upset when they face Jose Mourinho's team.
Shelvey was eager to stress that, despite recent results, Newcastle are coping well for a newly promoted side.
Shelvey told the Chronicle: “There’s no bigger game than Man United away at Old Trafford.
“Our last two games have been disappointing, to be honest. I thought we should have been two or three goals up by half-time [against Bournemouth] with the chances we had.
“Obviously, we threw it away at the end, and in the Burnley game I thought we did enough to warrant at least a draw to be honest.
“You’re going to lose games in this league. It’s part and parcel of football at the end of the day.
“I think people should remember how well we’ve actually done this season. We’re sitting in 11th place and we’re a newly-promoted team."
Shelvey is likely to have a major part to play for Newcastle on Saturday and the 25-year-old will certainly have to keep his discipline and composure in a difficult fixture.
Although he was overlooked by Gareth Southgate for inclusion in the England squad despite several players being unavailable, Shelvey has been a regular in the Newcastle midfield of late and has started his side's last five matches in a row in the Premier League.
Shelvey received a considerable amount of criticism for his actions against Tottenham Hotspur earlier in the season when he was dismissed for stamping on Dele Alli but the Newcastle player will certainly be eager to show this weekend that he can remain calm on the big stage.