Oerson found space on the right and beat Tsepo Motsoeneng from 18-yards out.
It was from Graham King’s corner that Mogogi Gabonamong’s header gave Santos the lead.
Eleazar Rodgers had missed a very good chance earlier and Tony Tsabedze could have added another goal but Patrick Tignyemb was up to the task.
Tlou Segolela came close for Celtic and so did Sandile Ndlovu. Then Motsoeneng made an excellent save from Kanono’s free kick.
But the Siwelele faithful were sent into a frenzy when Oerson slotted the late equaliser.