Paulo Dybala and Gonzalo Higuain allowed Juventus to conquer San Siro, end Inter's perfect start and take the top of the table in a spectacular Derby d'Italia.
This was the first time Antonio Conte faced his former club and an early Scudetto clash, with Juve going in two points behind an Inter side that had won six out of six.
Romelu Lukaku shook off a muscular problem to start, with Danilo D'Ambrosio picked instead of Antonio Candreva and Alexis Sanchez suspended. Juve missed Giorgio Chiellini, Danilo, Mattia De Sciglio, Douglas Costa and Marko Pjaca, but Maurizio Sarri surprised by choosing Dybala and Federico Bernardeschi instead of Gonzalo Higuain and Aaron Ramsey.
The visitors immediately had an aggressive start and took the lead within four minutes, as Dybala rushed forward from midfield and smashed his angled drive between Milan Skriniar's legs to surprise Samir Handanovic.
Incredibly, this was the first time Inter had been trailing in Serie A this season, the first goal conceded at San Siro, the first let
It was end to end from the get-go, as Cristiano Ronaldo unleashed a scorcher from the edge of the box that smashed against the crossbar.
Moments later Lautaro Martinez sent Lukaku one-on-one with Leonardo Bonucci, but the defender stood his ground.
Inter were awarded a penalty when Matthijs de Ligt went in clumsily to anticipate Lautaro Martinez and made contact with his arm. Lautaro stepped up and converted the resulting penalty, drilling it under Wojciech Szczesny's arm at the near bottom corner.
Lautaro Martinez almost scored a spectacular strike from a tough angle, as the half-volley was dipping and Szczesny flew to palm it away from the far top corner.
Inter lost Stefano Sensi to a groin injury, making way for Matias Vecino. Juan Cuadrado's almost suicidal back-pass flashed in front of Lautaro Martinez and Ronaldo's rocket was beaten away with real difficulty by Handanovic.
Moments later, Ronaldo had the ball in the back of the net with a daisy-cutter, but Dybala was offside during the build-up and it was disallowed.
With the final kick of the half, Dybala went down in the box after nutmegging Godin, but the referee waved play on. A row broke out in the tunnel on the way off for half-time, with Dybala and substitute goalkeeper Daniele Padelli arguing.
Handanovic caught a long-range Bernardeschi strike, then rushed off his line to put off Dybala, as Juve took control of the second half and Sensi's absence was sorely felt.
Sarri wanted to go for the jugular, so introduced Higuain for Bernardeschi, using Pipita with Dybala and Ronaldo together, but it left Juve a little unbalanced.
De Ligt made a crucial tackle on Lukaku, then Lautaro Martinez rode two challenges before Alex Sandro's eventual lunge.
Matias Vecino almost scored a bizarre goal on 69 minutes, as his shot took a huge deflection off De Ligt and bounced off the upright with Szczesny stranded.
Handanovic used his legs to parry a Ronaldo angled drive at the near post. Both sides had penalty appeals waved away, Lukaku for a shoulder-to-shoulder with Bonucci, Rodrigo Bentancur for a Brozovic tackle from behind.
The restoration of balance with the 4-3-1-2 formation worked for Juventus, as they restored their lead. Ronaldo and Bentancur exchanged quick passes to send Higuain through, he took a touch and rifled the right-foot finish low past Handanovic from 12 yards. It was the first real example of Sarriball we've seen from Juve this season in the build-up with 24 passes.
Szczesny rushed off his line to parry from Vecino, sent clear by an intelligent D'Ambrosio slide-rule pass, as Inter poured forward with a series of corners.