Al Ahly suffered their first defeat of the CAF Champions League group stages after losing 1-0 to Khanyisa Mayo's CR Belouizdad on Friday night.
Qualification to knockouts awaited the reigning champions, who decided to name Percy Tau on the bench while the home side continued with Mayo in the attack.
The tempo right after kick-off were off to a decent start as Ahly came close through to going ahead from a promising free-kick by Yahya Attiat-Allah.
It didn't stop there for the tournament record-holders who intensified more pressure and witnessed a scorcher from range by Hussein El Shahat shaved the opposing goal.
Ahly continued to be the more fancied as the spell raged and had Rami Rabia flash wide of the mark from a delivery by El Shahat.
The Algerian outfit responded a minute from the interval with Mohamed Islam Belkhir going high and wide from inside the box following a clever pass into the channels.
Mayo got a sight of goal too as the half continued to tick away and saw his goal-bound header from the area put Mohamed El Shenawy to a save.
With neither going to the bench in so far as bringing on substitutes before the commencement of the second half, the tie remained evenly poised with a lot at stake.
Belouizdad fancied their chances early in the half with Aimen Mahous going wide from a perfectly struck free-kick well outside the area.
Another moment showed the host way a little later where a loose ball from a corner fell in the path of Mohamed Naoufel Khacef, but he failed to hit the net.
Mahous didn't continue the rest of the match and was substituted for one-time Leicester City striker Islam Slimani towards the final quarter of play.
Belouizdad snatched victory at the death with Naoufel Khacef applying a stern finish in the bottom-corner as the Cairo giants fluffed their lines.
The loss denied the defending champions early qualification to the knockout stages, as Belouizdad's campaign received a shot in the arm.