Having beaten ES Tunis and drawn with CS Sfaxien in the opening two Group B fixtures, Setif had a great opportunity to enhance their chances of qualifying from the pool by beating the Libyan side.
And the Algerian outfit looked to have delivered three points at the Stade du 8 Mai, when Rachid Nadji scored his second goal of the group stages with a scrambled effort in the 44th minute.
However, there was to be a dramatic twist as Fetori kept his composure from 12 yards to level for the away side in the 91st minute.
With the match heading into the break at 0-0, it was Nadji who made the breakthrough for Rabah Saadane's on the stroke of half-time.
The ball fell kindly for the 26-year-old who rounded Wisam El Boudi in the visitors' goal before scrambling home.
Nadji went close to a second in the latter stages of the second half, but he saw his effort cleared off the line.
Al Ahli would make the most of that reprieve when they were rewarded a late spot-kick, and Fetori made no mistake with the penalty, as the race for the semi-finals remained wide open in Group B.