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.
In the first home game for the seven-time defending champions, Paulo Dybala and Douglas Costa started on the bench, with coach Massimiliano Allegri opting for Federico Bernardeschi and Mandzukic to spearhead the frontline with Ronaldo.
Ronaldo couldn't find proper contact with the ball rolling under his foot, thankfully Mario Mandzukic was on hand to spare his teammates' blushes by tapping the ball into the net.
Although Ronaldo would be expected to start week in week out for Juventus, something which seems more likely after Gonzalo Higuaín joined Milan, manager Allegri claims the Portugal worldwide will be forced to feature in a number of cameo appearances throughout the season.
Bernardeschi had another effort blocked and Ronaldo was denied before the interval when Thomas Strakosha saved his low shot.
"He understood that the Italian championship is completely different from the Spanish one and he has understood the DNA of Juventus".
"I have a very strong squad and have to evaluate everyone".
"We went from being frenetic at times to falling asleep at others".
Pjanic put Juve ahead with half an hour gone in Turin and Mandzukic made victory certain 15 minutes from time.
There was another big cheer shortly afterwards when former Napoli striker Higuain shot high and wide from his only real opening of the match.
Three points for both teams, with Lazio aiming to get its first points of the season.