Carlos Bacca scored a hat trick but AC Milan needed an injury-time penalty save from teenage goalkeeper Gianluigi Donnarumma to secure a 3-2 win against Torino at San Siro.
Bacca bagged his first with a diving header to convert Ignazio Abate's cross after 38 minutes but three minutes into the second half Torino, managed by Sinisa Mihajlovic who was sacked by the Rossoneri last season, were level when Andrea Belotti headed home a Cristian Molinaro cross.
Bacca immediately restored the hosts' lead with a tidy piece of control and an assured finish after he was picked out inside the penalty area by M'Baye Niang.
The Colombia international completed his treble in the 62nd minute from the penalty spot, blasting his shot straight down the middle.
Lazio edged a hugely entertaining game at Atalanta 4-3 to make a winning start to the new season.
The Biancocelesti looked like strolling to a comfortable victory as goals from Ciro Immobile, Wesley Hoedt and Cristiano Lombardi gave them a three-goal cushion going into half-time.
However, Atalanta rallied after the break and two quick goals from Franck Kessie put the hosts right back in contention with over 25 minutes to play.
Danilo Cataldi extended Lazio's lead in the final minute to secure the three points for Simone Inzaghi's team but Andrea Petagna struck in injury time to ensure the winning margin was just the solitary goal.
It was not such a good day for new Inter Milan coach Frank de Boer, though, as his side crashed to a 2-0 defeat at Chievo.
Valter Birsa bagged both goals in the second half to leave De Boer, who replaced Roberto Mancini as manager less than two weeks ago, with much to ponder.
Last season's runners-up Napoli were also given a scare, needing a second-half double from Dries Mertens to salvage a 2-2 draw against league new-boys Pescara at Stadio Adriatico.
First-half goals from Ahmed Benali and Gianluca Caprari had put Pescara, promoted via the playoffs after finishing fourth in Serie B, in control but Mertens struck twice in the space of three minutes just after the hour to drag Napoli level.
Genoa also had to stage a fight back before beating promoted Cagliari 3-1. Marco Borriello's 67th-minute goal put the visitors ahead but Genoa responded with three goals in the final 11 minutes from Olivier Ntcham, Diego Laxalt and Luca Rigoni to take the points.
Bologna got their campaign off to a winning start after beating newcomers Crotone 1-0 with a late Mattia Destro goal, while Luis Muriel's 38th-minute effort earned Sampdoria a 1-0 triumph over an Empoli side who lost Massimo Maccarone to a late red card.
It was a similar story at Palermo, where visitors Sassuolo claimed a 1-0 win thanks to Domenico Berardi's 32nd-minute penalty before the hosts had Slobodan Rajkovic sent off in the closing stages.