كتب : Ahmad Saied
Hassan, who played to cover the absence of starting midfielders Mohamed Shawki and Hossam Ashour, scored the winner in the 70th minute.
Islam Al-Shater came on as a substitute two minutes later but he was sent off in the stoppage time for collecting two yellow cards. This was his second red card in as many matches.
Ahli now have 41 points, nine clear off second-placed Ismaili before both sides clash on Sunday.
Mohamed Abou-Treika almost put Ahli ahead in the ninth minute when he tested Tanta's keeper Emad Fathi with a powerful shot but his effort cannoned off the frame of the goal.
Tanta answered quickly when veteran striker Bedir Al-Sherbini was released inside the area but he shot poorly into the hands of Ahli goalie Essam Al-Hadari.
Abou-Treika came close again in the first-half, controlling a neat cross from Flavio Amado before shooting from close range but Fathi timed his dive well to block the ball.
The African champions took the lead midway through the second period through Hassan.
Anticipating the ball on the edge of the box, Hassan found the ball falling into his path after Fathi boxed out a corner-kick from the right-hand side.
With the keeper left stranded, Hassan chipped a perfectly-weighted ball over all heads and his shot settled into the net despite a desperate attempt from a defender to clear it off the line.
In the 72nd minute, Al-Shater, who was introduced for Ahmed Sedik, received a caution after a harsh challenge on Al-Sayed Hamdi.
Al-Shater completed a personal misery when he handled the ball on the edge of the area in the 93rd minute only to be handed a second booking and leave the pitch with a red card.
The international winger missed his side's 2-1 victory over Zamalek in the Cairo derby earlier this week after being sent-off against ENPPI in the previous game despite coming off the bench during the interval.