Inter maintained their 100 per cent record in Serie A as Antonio Conte's side recorded a 1-0 win over Lazio at San Siro on Wednesday.
The hosts, fresh from a 2-0 derby triumph over AC Milan at the weekend, opened the scoring with the first effort at goal when Danilo D'Ambrosio headed home after 23 minutes.
Lazio ought to have been level before the interval, with Joaquin Correa guilty of wasting two excellent opportunities against an in-form Samir Handanovic.
The second-half introduction of Ciro Immobile, benched after his adverse reaction at being substituted in the 2-0 win over Parma on Sunday, failed to prompt a Lazio comeback.
Conte's men have now won five from five to mark themselves out as the most likely challengers to Juventus' top-flight supremacy.
Inter dominated possession from the start but it was the visitors who threatened first.
Felipe Caicedo ran into the penalty area but his heavy touch allowed the alert Handanovic - making his 300th appearance in all competitions for the Nerazzurri - to clean up the loose ball.
When the first attempt finally arrived it found the back of the net, D'Ambrosio leaping above Jony to nod in Cristiano Biraghi's cross.
Lazio sought a swift response and forced Handanovic into a superb save to tip Correa's curling strike over the crossbar.
With the game suddenly stretched, Romelu Lukaku drilled narrowly wide and Correa fluffed his lines when clean through on goal.
Handanovic again came to Inter's rescue with a reflex save from Correa's close-range shot to ensure his team were ahead at the break.
Correa was soon at it again in the second half, jumping to head a corner wide from just six yards, and Simone Inzaghi could wait no longer to bring on Immobile.
A fine double save from Thomas Strakosha, denying first Nicolo Barella then Matteo Politano, kept Lazio in the contest before the hour mark, while substitute Lautaro Martinez fired narrowly wide in added time.
Yet despite those reprieves, Inzaghi's side were unable to find an equaliser to put an end to Inter's perfect start to the Serie A season.
What does it mean? Inter have the stomach for a title tussle
Following a derby win over their city rivals, Inter could have fallen victim to a touch of complacency in this match. However, Conte's team produced another impressive showing, combining defensive solidity – they have still only conceded one league goal this term – with a calm and measured approach on the ball.
They face Juve early next month in what is shaping up to be an intriguing contest.
A big hand for super Samir
That Inter kept their excellent defensive record intact was in large part down to Handanovic. On several occasions it was solely the Slovenian who stood between Lazio and a goal that would have changed the course of the game.
You must be Joaquin!
Creating chances was not really Lazio's problem; they had enough in the first half alone to have seriously troubled their opponents. Correa was more culpable than anyone in their failure to make a breakthrough. A little composure could have made a big difference.
Both sides are in domestic action at the weekend before a return to continental competition, with Inter off to Sampdoria and then Barcelona, while Lazio have back-to-back home games against Genoa and Rennes.