All eyes pre-match were on the Portuguese, but he wasn't overly involved early on as the visitors settled quickly.
Senad Lulic and Adam Marusic both brought routine saves from Wojciech Szczesny, before Sami Khedira rattled the post at the other end after Ronaldo had the ball nicked off his toe.
Lazio performed admirably throughout, but they were undone by a piece of genuine quality on the half-hour mark.
A cross from the right was only cleared as far as Mirlaem Pajnic on the edge of the box and the Bosnian took full advantage to fire home first time with a wonderful low volley that left Thomas Strakosha grasping at thin air.
However, the visitors reacted well to going behind, with star man Ciro Immobile looking to force an opening through sheer brute strength, before the experienced Marco Parolo headed an inviting Sergej Milinkovic-Savic cross from the left over the bar when completely unmarked in first-half stoppage time.
The stats did not make pretty reading for Ronaldo at the break, with the Portuguese having recorded just one touch inside the Lazio box during the first half and things didn't really improve for the Portugal star from there.
August 25, 2018
Lazio had the better of the first 10 minutes after the restart as Luis Alberto curled narrowly wide, though the game grew increasingly bitty as the foul count rose.
Ronaldo could have scored his first for his new club when meeting a left-wing corner, but Wallace did just enough to put him off at the far post.
When the 33-year-old did hit the target, Strakosha was there to deny him, with the Albania international producing a stunning fingertip save to keep out Ronaldo's dipping drive from 25 yards.
With 15 minutes to go Ronaldo could not help but laugh at his own misfortune as he could only screw Joao Cancelo's low cross from the right up into the air with the goal gaping after another last-ditch intervention from Strakosha, but on this occasion Mario Mandzukic was on hand to fire the loose ball into the back of the unguarded net.
The hosts cruised to victory from there on out to maintain their 100% start to their Serie A title defence. The picture after two games is somewhat bleaker for Lazio, who are yet to claim a point.
August 25, 2018