In a late game played at the Seeb Sports Stadium, Fanja, eight-time champion and one of the title contenders, began its campaign in the 2015-2016 season with a confident 3-0 win over Muscat Club.
The national team strike pair of Imad al Hosni and Abdulaziz al Miqbali, along with Brazilian import Jaja, were on target for Fanja.
Earlier, the opening match of the OPL witnessed a clash between former winners Suwaiq and hosts Al Nasr at the Saada Sports Complex in Salalah. Suwaiq got the better of its opponent with a hard-fought 2-1 win.
On Monday, the remaining four matches of the first round will be played, with defending champion Al Arouba launching its title defence with a visit to Salalah against Salalah Club.
The other games will have nine-time champion Dhofar taking on hosts Al Shabab at the Seeb Sports Stadium, Al Khabourah meeting Saham in an all-Batinah clash at the Sohar Sports Complex and Sohar hosting Sur at the same venue in an earlier game.