Giorgio Chiellini has struck for champions Juventus to seal a 1-0 win at Parma in the opening game of the Italian Serie A season.
Last season's runners-up Napoli won 4-3 at Fiorentina in later action on Saturday with a brace from captain Lorenzo Insigne, as the Neapolitans' two other strikers Dries Mertens and Jose Callejon were also on target.
Juventus's veteran captain crowned an aggressive start from the Bianconeri with a close-range flick on 21 minutes after his defensive colleague Alex Sandro sent the ball into the box.
Cristiano Ronaldo missed three attempts before beating Parma keeper Luigi Sepe but had the goal disallowed for offside after a lengthy review from the video assistant referee.
The Portuguese fired another high drive on the hour and was then twice denied by Sepe as he played next to Gonzalo Higuain, his ex-Real Madrid teammate who is back at Juventus after loans to AC Milan and Chelsea.
Parma's Roberto Inglese fired the first shot on target on 13 minutes, while his teammate Gervinho had few chances to produce his trademark fast runs.
Cooling breaks were called in each half of the late-afternoon fixture and Sandro said both teams lost strength towards the end of the physical game.
"This is normal at the start of the season. We must find more energy, but we are on the right path. In the second half we tried to have more control and run less," he said.
"I think the coach (Maurizio Sarri) will be happy as we clinched the three points, but I am sure we have a few things to improve."
New Juventus coach Sarri was at home with pneumonia and is likely to miss the next game against his former team Napoli.
The Naples side fell behind when VAR was called in at Florence's Artemio Franchi to ascertain Piotr Zielinski's ball handling.
La Viola's new signing Erick Pulgar converted on nine minutes, but Mertens levelled with a swerving drive on 38 and was floored for Insigne's penalty five minutes later.
Nikola Milenkovic's header levelled for the hosts after the break and Callejon fired the Neapolitans' third goal low into the far corner in the 56th.
Kevin-Prince Boateng, also a new arrival at La Viola, struck in similar fashion for 3-3 on 65 minutes, two before Insigne nodded in the winner off Callejon.