Khabourah took the lead at the half-hour mark through Said Obaid’s goal and hung on to the advantage till the 71st minute when Saham's Musab al Sharqi scored the equaliser.
Breiki then scored the winner with five minutes left for the final whistle.
Saham's win ensured that the first round of the OPL witnessed no draws. Defending champion Al Arouba, Fanja, Dhofar and Al Suwaiq, along with Al Musannah and Sohar, all got off to winning starts.
The second round will be played on Thursday and Friday, with a blockbuster clash between Arouba and last year's runner-up Fanja to be played at the Sultan Qaboos Sports Complex on Friday, starting at 5.15pm.
Other fixtures: Thursday: Muscat vs Al Nasr, Saham vs Al Nahda, Al Suwaiq vs Khabourah, Musannah vs Al Shabab; Friday: Dhofar vs Sohar, Sur vs Salalah.