The Nassr captain, who came into the match in red-hot form, opened the scoring at Mrsool Park on four minutes, when he collected a Sadio Mane pass and sent his shot low past Ahli goalkeeper Edouard Mendy.
Brazilian Talisca then doubled the hosts’ lead on 17 minutes, heading home Aymeric Laporte’s knock-back from Alex Telles’ deep free-kick.
Yet Ahli, who entered the contest one spot above Nassr in the table in fifth, halved the deficit right on the half hour. Defender Mohammed Al Majhad played a beautiful ball from deep to set Franck Kessie through on goal, and the former AC Milan and Barcelona midfielder finished expertly past Nawaf Al Aqidi in the Nassr goal.
Nassr, though, restored their advantage deep into first-half injury-time. A sweeping move ended with Talisca collecting the ball just inside the Ahli area and curling a beautiful shot into the net off the crossbar. It marked a second stunning effort from the forward in the past two rounds.
However, Ahli dragged themselves back into the game right at the beginning of the second half. This time, Talisca turned villain after he was judged to have tripped Bassam Al Haryaii in his own penalty area. Riyad Mahrez sent Al Aqidi the wrong way from the spot.
Almost in an instant, Ronaldo doubled Nassr’s lead again. The Portuguese forward, 38, pounced on a loose ball well outside the Ahli area, cut inside his marker, and drove a fierce low shot past Mendy. It marked Ronaldo’s ninth goal in his past five league matches. He sits atop the early season scoring charts.
There was still time for a grandstand finish. With two minutes remaining, substitute Firas Al Buraikan met a grounded Mahrez cross to place home and set up a frantic finale. It was the former Nassr striker's first goal for Ahli following his recent move from Al Fateh.
Then, well into the 10 extra minutes of injury-time, Ahli thought they had snatched a point, only for Fahad Al Rashidi’s header from Mahrez’s free-kick to skid off the crossbar.
Nassr, runners-up last season, held on to draw level in the table with Ahli. They now sit only three points off leaders - and champions - Al Ittihad after seven rounds.