Alen Ahmedhodzic put United ahead early in the second half before a Paul Mullin penalty drew Wrexham level
Berge scores United's third on counter to set up fifth round tie against Tottenham Hotspur
National league title contenders Wrexham have been beaten after two thrilling ties
Further changes also include a full debut for Ismaila Coulibaly.
Iliman Ndiaye was spotted playing in James McAtee in a nice domestic move