Sergej Milinkovic-Savic grabbed a last-gasp winner for Lazio at the Stadio Bentegodi, their first victory here since 2014.
The Flying Donkeys were feeling confident after a surprise 2-1 opening round victory away to Udinese, whereas Lazio followed up the Italian Super Cup triumph with a disappointing goalless home draw with Spal. Riccardo Meggiorini and Gianluca Gaudino were sidelined for the hosts, while the Aquile missed Felipe Anderson, Patric, Cristiano Lombardi and contract rebel Keita Balde Diao.
Lazio secured only one win in their previous six Serie A fixtures against Chievo, home and away, losing two and drawing three. Their most recent victory at the Bentegodi was 2-0 in February 2014.
Luis Alberto whipped in a corner for the opening goal and Stefano Sorrentino flapped aimlessly at it, allowing Ciro Immobile to nod in at the back post.
Chievo threatened an equaliser, Thomas Strakosha fingertipping a Lucas Castro header out from under the bar, while Immobile failed to finish off a Luis Alberto counter-attack.
The hosts did draw level after a chaotic move, as the loose ball fell to Manuel Pucciarelli to blast home.
Strakosha fingertipped a Valter Birsa dipping missile round the post from midfield, while Immobile hit the side-netting with a volley after an inspired Sergej Milinkovic-Savic chipped pass.
Lazio won it at the death with another magnificent moment from Milinkovic-Savic. This time he went for it himself, unleashing a right-foot missile into the top corner from distance.