Barmby and Paddy McNair to create a simple chance. James Weir shot wide and Barmby deserved a finishing touch in the middle after a purposeful run into the box but there was no route back in the game for a second time.
England schoolboy winger Demetre Mitchell came off the bench for his Under-18 debut but Palace held out quite comfortably, frustratingly making two substitutions in stoppage time to help run down the clock.
United: Sutherland; Grimshaw, McConnell, McNair, Evans; Weir, Pearson, Pereira (Mitchell 76), Barmby, Daehli; Byrne. Subs not used: Gollini, Barber, Fletcher, Harrop.