The 25-year-old said he had faith in manager Rafa Benitez's ability to set the side up to be competitive against Jose Mourinho's team, who suffered a 1-0 defeat at Chelsea in their last league game before the international break.
"Rafa knows this league, he knows how to set teams up and how to get results and I'm sure that we'll go there and give a good account of ourselves, and hopefully come away with something," added Shelvey.
Promoted Newcastle dropped to 11th in the league following 1-0 defeats by Burnley and Bournemouth but Shelvey said form counted for little.
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"We could go and do something against Man United - that's how weird this league is," he added. "Anyone can beat anyone, so I think there's enough for us to survive in this league."
(Reporting by Shrivathsa Sridhar in Bengaluru; Editing by Peter Rutherford)
