كتب : Hatem Maher
Striker Fadl inadvertently handled the ball into the net after a free kick from right-back Fathi to give Ahli, who were roared on by a sell-out crowd at Cairo Stadium, the lead seven minutes before the break.
Fathi left the keeper with no chance with a powerful drive eight minutes past the hour mark to double their advantage.
However, Esperance were given a lifeline few minutes later after captain Oussama Darragi made the most of a mistake from keeper Sherif Ekrami to reduce the arrears.
A tense match saw Esperance's fans clash with security personnel, ripping up seats and throwing them midway through the second half.
TV cameras also caught a dozen of the away supporters beating up two stewards.
Ahli will be looking to preserve their narrow advantage when they face Esperance in the second leg in two weeks time.
The six-time African champions are aiming to book a place in the elite competition's final for the fifth time in six years.
Controversial Goal
Esperance defended in numbers in the first half to make life difficult for an Ahli side who played with two strikers in Fadl and Francis Doe.
The visitors relied on the physical prowess and pace of Nigerian striker Michael Eneramo, who shouldered the responsibility of rounding off their counter attacks.
He drilled a low cross home after nine minutes but his goal was correctly ruled out for offside.
Ahli laid siege to Esperance area but barely found spaces to create goalscoring opportunities, with the likes of Mohamed Barakat and Mohamed Abou-Treika struggling to feed the strikers.
But Barakat, a natural right-sided midfielder who played on the left due to the absence of the injured Sayed Moawad, could have opened the scoring in the 31st minute.
He ran onto a flick from makeshift left-back Sherif Abdul-Fadil and escaped the attention of his marker but his low shot from a tight angle went just wide of the post.
Ahli broke the resistance of Esperance in the 38th minute, albeit in a highly controversial fashion.
Esperance's shaky keeper Wassim Naouara failed to handle a left-wing free kick from Fathi as the ball struck the arm of Fadl, who was the quickest to react, and rolled into the net.
The referee allowed the goal to stand, prompting Esperance's angry players to surround him in protest at his decision.
Defense Split
Esperance could not hold firm in the early stages of the second half as Ahli split open their defense on several occasions.
Fadl was guilty of spurning a golden opportunity in the 53rd minute that eventually led to his substitution few minutes later.
Doe outpaced his marker to control a long ball and skip past Naouara, whose untimely interception almost gifted Ahli a second goal.
The Liberian lost his balance though to miss out on the chance of directly slipping the ball into an empty but he still managed to pull it back to Fadl, who fired over the bar with the goal at his mercy.
Barakat was also unlucky not to score in the 55th minute when his low shot from inside the area was cleared off the line by Esperance defender Walid Hichiri.
Ahli's pressure finally paid dividends on 68 minutes when Abou-Treika laid off the ball to the onrushing Fathi, whose fierce angled drive went into the top corner of the net.
The Red Devils looked capable of adding to their tally but Esperance scored against the run of play in the 73rd minute to ensure they would still have a good chance to reach the final.
Ekrami spilled an innocuous free kick and Darragi bounced to notch home on the rebound.