Antonio Conte set a club record as he became the first Inter coach to win his first five Serie A games at the helm after overseeing a 1-0 victory against Lazio.
The Nerazzurri extended their perfect start to the top-flight season courtesy of Danilo D'Ambrosio's first-half header at San Siro.
Wednesday's triumph took Inter back above Juventus at the summit, making it a maximum return of 15 points so far in a promising campaign.
Conte, who succeeded Luciano Spalletti during the close season, won three Serie A titles while in charge of Juve.
He will now hope to bring the Scudetto to Inter, who were last crowned champions in 2009-10.