Muhadjir Hakizimana’s 27th minute goal separated the two sides handing victory to the army side, who finished with a man less after Hakizimana was sent off five minutes before recess.
Before the break, forward Shassir Nahimana had the chance to draw level but Yves Kimenyi denied him with a good save.
Back from recess, Rayon made several onslaughts in search of the equalizer, but failed to convert their chances into goals.
Since 1995, Rayon and APR have created a bitter rivalry. It was the 85th official match in all competitions between the two sides and the 46th league meeting since 1995. APR has managed 35 wins against Rayon Sports’ 23 while 27 games have ended in draws.