Nyambayar made the better start and had established a 6-4 lead by the end of the opening round. He was first to the punch and with greater accuracy.
The Russian was struggling to get to grips with his opponent, who was growing in confidence as he landed a number of shots.
Aloian trailed by three points by the third round and nothing was clicking for him. His timing seemed to be off as the Mongolian continued to slip his shots.
Nyambayar was relatively untroubled in the final round as he closed out a 15-11 victory.