United can confirm goalkeeper Ron-Robert Zieler has broken a bone in his arm.
Zieler, a German youth international, suffered the injury in the Reserves’ 3-3 draw at St James’ Park on Monday night.
With the Reds leading 1-0 in the first half, the 20-year-old stopper punched clear a cross but simultaneously collided with a Newcastle attacker. He received lengthy treatment by the side of the pitch before being replaced by Conor Devlin.
Zieler, who enjoyed a loan spell earlier this season at Northampton Town, will be further assessed on Wednesday 1 April.