A solitary goal win for Sohar over Al Khabourah helped it finish 12th in the OPL table with 31 points. Mohammed al Ajmi slammed the winner in the 21st minute for Sohar.
The Oman Football Association (OFA) announced on Tuesday that the first-leg of the playoff match will be played at the Sultan Qaboos Sports Complex on May 28 while the return leg in Sohar on May 31. The match in Sohar will formally bring the curtains down for the domestic season.
Rustaq had finished third in the first division to earn a chance to fight for a place in the OPL.
Muscat and Salalah finished first and second in the first division respectively to gain promotion for next season's OPL.
On Monday, the last round of the OPL matches witnessed champion Al Arouba going down 0-2 to Al Shabab while Fanja rode on national team player Raeed Ibrahim's goal to beat Al Nasr 1-0 at the Al Saada Sports Complex in Salalah.
The win helped eight-time winner Fanja clinch the runner-up spot with 47 points. Al Arouba finished on top with 49 points and under coach Philippe Burle of France completed a rare domestic double, winning the OPL and HM’s Cup titles.
Elsewhere, Sur edged past Bausher 1-0 at the Sur Sports Complex to end at third place with 46 points, a small consolation after it lost to Arouba in the HM's Cup final at the same venue on Friday.
Al Nasr finished fourth with 41 points.
The defeat to Sur completed a torrid season for Bausher, which was relegated along with Seeb. Bausher could muster only 21 points while Seeb ended up with just 18.
In the other matches, Al Nahda celebrated the OFA's Court of Arbitration verdict to reinstate its six points that were docked after it pulled out of an OPL match against Dhofar earlier in the season, with a victory.
The 2014 OPL winner, Nahda, beat Saham 3-2 at the Al Buraimi Sports Complex. The win helped it climb to eighth spot with 33 points and will play Dhofar (38) in their last round game on May 28 in Salalah. The court had ordered the match to be replayed.
And Al Suwaiq's 3-2 victory over Al Musannah avoided the possibility of the former winner to play a playoff as it managed to edge Sohar for the 11th place with 31 points.