Sami Khedira netted his second goal in as many rounds of the Serie A season to help champions Juventus win 1-0 at Lazio Saturday.
The Bianconeri moved onto six points despite a poor showing in the stifling heat at Rome's Stadio Olimpico, which led to a 27th-minute cooling break called for the first time in the Italian top flight.
“I think that in the first half we did not have enough movement,” Khedira said. “In the second we had more circulation, we played much better and it was easier for us to score.”
In a fairly dull first half, Lazio goalkeeper Federico Marchetti had little difficulty saving from Paulo Dybala and Kwadwo Asamoah.
Twelve minutes after the break, Mario Mandzukic fired straight at Marchetti then Dybala missed narrowly before Khedira went close with a drive.
But the German international soon found the far corner of the net on 66 minutes off an assist by Dybala on the right.
Spanish substitute Patric fired over on 75 minutes, missing the hosts' first telling opportunity before Gianluigi Buffon stopped a Marco Parolo drive on 86 minutes. A last save from Marchetti denied substitute Marko Pjaca.
Later in Naples, Jose Callejon tapped in the winner after a brace from his new team-mate Arkadiusz Milik to edge nine-man AC Milan 4-2.
Milan defender Ignazio Abate botched a close-range deflection before Poland striker Milik on 18 flicked home undisturbed as Dries Mertens fired a swerving shot that came off the far post.
The in-form Mertens, who scored a brace in the league opener to salvage a 2-2 draw at Pescara, threatened again from the left in the 27th to see Gianluigi Donnarumma deflect bravely.
The Belgian international winger came again close from the right and Milik on 33 minutes nodded in the ensuing corner.
The Devils switched gears off the changing room, levelling from M'Baye Niang's tight-angle low shot and Spaniard Suso's smashing effort into the top left corner.
Another nasty shot from Mertens met Donnarumma's deflection, but Callejon pounced on 74.
One minute later Juraj Kucka was sent off for insulting the referee after being booked for a foul on Mertens.
In stoppage time, Alessio Romagnoli deflected into his own goal a cross from substitute Lorenzo Insigne.
Napoli coach Maurizio Sarri had been dismissed for his protests after the goal of Niang, who also left the pitch with two yellow cards three minutes from regulation time.
Eight games are set for Sunday.