Zamalek were on the verge of escaping with another 0-0 away draw in the CAF Confederation Cup but Morocco's RS Berkane were still able to snatch a first-leg advantage in the final after striking deep in stoppage time.
Having wasted several goal-scoring chances, especially in the first half, Fo Doh Laba finished off a neatly-worked breakaway four minutes into the additional time to spark wild celebrations at the Berkane Municipal Stadium.
The competition's leading scorer took his tally to eight goals as he atoned for a couple of glaring misses before the break.
Zamalek could have also netted an away goal in the second half, only for winger Mahmoud Kahraba to miss a sitter following a one-on-one situation.
The White Knights will attempt to overturn the narrow deficit when they host Berkane next Sunday at Alexandria's Borg El-Arab Stadium as they chase their first ever Confederation Cup title.
Although Zamalek had an early chance to shock the home crowd when central defender Mahmoud Alaa volleyed over the crossbar after being found unmarked at the far post, Berkane were the more dangerous in the first half.
Their repeated crosses from the right flank unsettled Zamalek's defence, which was supported by defensive midfielder Tarek Hamed who acted as a third central defender for most of the game.
A glancing header from Laba struck the woodwork after a free kick was floated from the right on 15 minutes and the post also denied a close-range effort from the Togolese marksman seven minutes before the break.
Zamalek looked like threatening every time they launched a counter attack, with winger Kahraba's nifty footwork causing menace down the left. However, they were often let down by their final touches.
Berkane eased off in the second half, with Zamalek appearing largely comfortable at the back for long spells.
The hosts had a penalty claim waved away by the referee following a VAR review as Hamed allegedly handled the ball in the area.
Kahraba could have stunned the home crowd in the 68th minute, breaking clear following a threaded pass from lone striker Omar El-Said but hitting a poor low shot that missed the target with the goal at his mercy.
Zamalek were punished at the death, Laba superbly controlling a long ball on the left and shaking off two defenders as he made a jinking run into the area.
He fed Souhail Yechou and received a return back pass with an unstoppable drive into the roof of the net.