Steve Bruce could welcome back Sean Longstaff and Isaac Hayden for Sunday's clash with Liverpool.
However, Sweden international Emil Krafth is a doubt after his ankle knock sustained away to Brighton & Hove Albion.
United still have Jamaal Lascelles, Florian Lejeune, Ciaran Clark, Fabian Schar are all out and Paul Dummet is ineligible.
Hayden could step in as an emergency centre-back, Bruce said: "We might have Isaac and Sean back for the weekend.
"Emil took a nasty whack and is a doubt.
"We have six centre-backs on the books and five are injured.
"We have been unfortunate with injuries."
Bruce was cautious about playing Under-23 star Kell Watts from the start against the Reds.
Bruce added: "There is a possibility but the boy hasn't played for five months.
"It is a big ask to come in and make your debut after being out so long.
"That's in my thought process."
