Maguire has not played for the Red Devils since December 12 due to a groin problem which he picked up against Bayern Munich in the Champions League.
Shaw, meanwhile, has missed his side's last four games in all competitions due to an unspecified issue, but both players were back in training earlier this week and have been declared fit for the FA Cup contest.
Man United will again be missing Anthony Martial, Tyrell Malacia, Mason Mount and Victor Lindelof through injury, while Sofyan Amrabat and Andre Onana are in action at the Africa Cup of Nations.
There are two further doubts in the shape of Rashford and Evans, meanwhile, with Ten Hag revealing on Friday that both players are suffering with illnesses.
«It's a strong side and we have still some injuries, like [Victor] Lindelof and [Tyrell] Malacia,» Ten Hag told MUTV.
«This morning, Rashford was ill and Evans was ill. So we have to see how they recover but we have, for the rest, players returning, like Martinez, like Shaw, like Maguire, like Casemiro, which is a good thing.»
Casemiro was back on the bench against Tottenham Hotspur last time out after a lengthy period out with a hamstring problem, while Martinez made his return from a foot operation off the bench in the 2-2 draw.
Altay Bayindir has been confirmed as a starter on Sunday, with the Turkey international preparing to make his debut for the Red Devils due to Onana's presence at the Africa Cup of Nations.
Newport are 14th in the League Two table and will be the huge underdogs on Sunday, but Ten Hag has insisted
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