Qatar's Al-Sadd defeated Iran's Esteghlal 2-0 as Persepolis and Pakhtakor of Uzbekistan drew 1-1 in Tashkent in the second round of matches in the league phase of Asia's revamped continental championship.
Mahrez struck in the third minute in Dubai to put Al Ahli ahead after deftly controlling Ibanez's ball forward and the pair switched roles seven minutes before the break for the Brazilian to double the lead.
The win moves Al Ahli onto six points from two games in the western side of the draw after Matthias Jaissle's side started the campaign with a win over Iran's Persepolis two weeks ago.
Al Nassr secured their first win of the competition having drawn their opener against Iraq's Al-Shorta as goals from Sadio Mane and Ronaldo sealed a 2-1 victory in Riyadh.
Mane emerged through a crowd of players to meet Sultan Al-Ghannam's lofted ball into the area with a close-range header in first-half added time, giving goalkeeper Paulo Victor little chance.
Ronaldo then found the net with 14 minutes remaining, sweeping a left-foot shot into the top corner of Victor's goal to wrap up the victory for Stefano Pioli's side with Roger Guedes hitting a late consolation for Al Rayyan.
The victory was Al Nassr's fourth in a row in all competitions since former AC Milan manager Pioli replaced Luis Castro as head coach.
"We deserved to win," said Mane. "We started well, we controlled the game and created many chances.
"So far I think we've done well together (under Pioli), we've played four games, we've won four games and we can't expect more than this."
Persepolis were denied their first win despite seeing Ali Alipour score in the first minute as hosts Pakhtakor earned a draw with Dragan Ceran bending in a 59th-minute equaliser.
Al-Sadd secured their first victory after drawing with defending champions Al-Ain two weeks ago as Felix Sanchez's side downed Esteghlal.
A mistimed punch by goalkeeper Hossein Hosseini five minutes before halftime put Al-Sadd in front and Akram Afif's 68th-minute penalty sealed the win.
The second round of league phase matches in the western half of the draw continues on Tuesday when Al-Ain travel to Qatar to face Al-Gharafa while four-time continental champions Al-Hilal from Saudi Arabia host Al-Shorta.