In a must-win Group C game to advance to the quarterfinals, Arouba was held to a goalless draw by arch-rival Sur in a Sharqiyah derby at the Sur Sports Complex.
Muscat, with two wins and three draws topped the group to advance with Sur, which collected seven points from one win and four draws. Arouba could manage six points. Also in Group D action on Monday, Al Nasr trounced Dhofar 3-0 in Salalah to book a berth in the last-eight stage.
Despite the loss, Dhofar moved into the quarterfinals as group topper with nine points.
Nasr and Salalah had seven points each but the former sealed its place in the next stage on better goal-difference after Monday's big win.
Following the two matches on Monday, the quarterfinal line-up was completed.
The teams that made it to the last eight stage are Al Nahda, Sohar, Al Musannah, Fanja, Muscat, Sur, Dhofar and Al Nasr. According to an Oman Football Association official, the quarterfinal draw will be held in the coming days.