Nonetheless, he did record an unintentional assist for Mandzukic's decisive second goal on the night.
Piotr Zielinski scored twice as Napoli came from two goals behind to beat AC Milan 3-2 and give new coach Carlo Ancelotti an unforgettable home debut, especially as it came against the side where he spent eight seasons of his coaching career.
Sami Khedira hit the post inside the opening 20 minutes when the ball ran away from Ronaldo in the area, before Federico Bernardeschi cut in from the right to draw a superb stop from Thomas Strakosha with a teasing curler.
The closest Ronaldo came to breaking his duck was with a vicious dipping effort on the turn in the 71st minute, but it was brilliantly turned over the bar by the Albanian goalkeeper.
Lazio finished the first half strongly but Ciro Immobile, Sergej Milinkovic-Savic, Lulic and Marco Parolo all spurned opportunities. "If anything, we need to be more alert for the rebounds".
It appears that it takes time for Ronaldo to hit top form in a league season, not that he was playing against significantly weaker defences in Spain a year ago. I'm delighted with how Ronaldo is settling in'.
The win left Napoli, last season's runners-up under Maurizio Sarri, with six points from their first two games.
Giacomo Bonaventura sensationally opened for Milan after 15 minutes in the San Paulo Stadium with a Davide Calabria half-volley giving the visitors a two-goal advantage four minutes after the break.