Paulo Dybala scored twice as Juventus thrashed 10-man Lazio 3-0 to take what should prove to be a decisive nine-point lead into the Serie A run-in.
Only a serious collapse in the last four games will open the door for Napoli to snatch the title from the reigning champions, who opened the scoring in Turin through Mario Mandzukic just before half-time.
Dybala's double -- from a penalty shortly after Lazio lost Patric to a red card, and then at the end of a Sami Khedira counter -- put Juve in a position to claim the Italian championship with four more points.
Napoli's thumping 6-0 home win over Bologna meant Juve would not be able to celebrate winning a fifth straight Scudetto on Wednesday night but they had a job to do nevertheless.
Federico Marchetti thwarted them as they tried all manner of trick shots, the Lazio goalkeeper pouncing on Dybala's sneaky effort before diving to keep Paul Pogba's half-volley out at the far post.
French dynamo Pogba tried again, unsuccessfully, from distance and Marchetti reacted quickly to Dybala's bullet header to further frustrate Juve.
The spectacular and sublime were not working so the Bianconeri went for the obvious route to goal.
Hernanes' corner beat the entire Lazio defence to find Pogba, whose angled low cross met Mandzukic's feet for a close-range finish five minutes before the break.
The dismissal of Patric for a second yellow card just after the restart turned the tide firmly in Juve's favour and in the 51st minute they won a penalty when Santiago Gentiletti fouled Leonardo Bonucci.
Dybala converted for his 15th goal of the season and Juve's mission was all but complete.
Lazio, who had enjoyed a two-game winning bounce since Simone Inzaghi replaced Stefano Pioli as head coach, began to lose focus and were 3-0 down before 65 minutes were up.
Former Real Madrid midfielder Khedira supplied the clever through ball that Dybala swept up and powered beyond a stranded Marchetti to settle the tie.
The Argentine forward would have claimed a hat trick had his left-footed rocket fooled Marchetti, and substitute Simone Zaza was unlucky not to add gloss to the scoreline in the final five minutes.
Should Juve claim three points from their trip to Fiorentina on Sunday, they will be 12 points clear.
Napoli then travel to face third-placed Roma. A defeat in the capital would hand Juve the crown.