Inter moved four points clear at the Serie A summit thanks to a resounding 3-0 derby triumph over faltering rivals Milan on Sunday.
Lautaro Martinez scored twice and Romelu Lukaku was also on target, helping Antonio Conte's in-form side make it five wins in their past six league outings to take a firm grip on the title race in Italy.
This was the first time since April 2011 that the city rivals had met when occupying the top two positions in the table, with that season finishing with Milan crowned as champions.
A repeat for the Rossoneri looks increasingly unlikely as their worrying dip in form continued, though they were somewhat unfortunate to come up against a goalkeeper in supreme form.
Samir Handanovic twice repelled Zlatan Ibrahimovic in quick succession early in the second half before Martinez's second goal of the contest, with Lukaku then putting an emphatic seal on the victory in the 66th minute.
However, it was Martinez who had crucially headed Inter in front inside five minutes. Lukaku initially saw his attempted low cross blocked, but a second, floated delivery picked out his team-mate to head past Gianluigi Donnarumma, making his 200th Serie A appearance.
Milan were grateful Lukaku did not take a glorious opportunity before the break, the Belgian striker failing to apply the finishing touch to Ivan Perisic's inviting cross as he missed the ball completely.
Stefano Pioli's team started the second half with a flurry of opportunities; Handanovic spectacularly turned away an Ibrahimovic header at a corner before producing a point-blank block to again deny the Swede when the ball came back into the penalty area.
Inter's captain also pushed a rising drive from Sandro Tonali over the crossbar, maintaining a lead they soon doubled when a clinical counter-attacking move allowed Perisic to pick out Martinez, who fired in with his left foot.
Lukaku put the game well beyond Milan with a fine solo effort, finishing a powerful run from deep in Milan's half with a low shot that flashed beyond Donnarumma. In doing so, he became the first Inter player to score in four successive Serie A derbies since 1950.