Duhail created their first chance of the game inside two minutes when Olunga rose the highest to meet Edmilson Junior’s cross from the corner but headed just wide with the goal at his mercy.
Al Ahli, who also had a chance to qualify had they won the match, threatened with their first chance in the 17th minute when Driss Fettouhi tested goalkeeper Salah Zakaria from range and Edmilson chose to shoot straight at Mohammed Al Owais from a tight angle when he had the option of crossing.
The two teams went into the break tied at 0-0 and on resumption, it was Duhail who continued to attack Al Ahli but they had to wait until the 61st minute when Olunga lined up a free-kick from 25 yards out and powered in a shot below the Al Ahli wall and past keeper Al Owais for the opener.