Enjoying a superb start under new coach Vladimir Petkovic, Lazio have won their first three matches of the league season for the first time since 1974.
Hernanes put Lazio ahead with a superb solo effort in the fifth minute, evading two tackles before firing in a long-range left-foot shot which went in off the post.
The Brazilian also set up the second goal when he again left his marker for dead.
Although he was foiled by Chievo goalkeeper Stefano Sorrentino, Germany forward Miroslav Klose was on hand to score from the rebound in the 38th minute for his third goal of the season.
Hernanes produced another inspirational moment for the third goal as he burst down the left to the byline, then managed to squeeze the ball past the bemused Sorrentino from a narrow angle in the 74th minute.
Sergio Pellisier pulled one back for the hosts with an 83rd-minute penalty.
Napoli and title-holders Juventus also have a maximum nine points after both enjoyed 3-1 wins over Parma and Genoa while Sampdoria have a 100 percent record but have only eight points after having one deducted over the Calcioscommesse match-fixing scandal.
AS Roma, who produced a masterclass of attacking football as they won 3-1 at Inter Milan in their last game, squandered a 2-0 lead and lost 3-2 at home to Bologna while Udinese also blew a 2-0 goal advantage in a 2-2 draw at Siena.
Argentine forward Maxi Lopez scored twice and Paraguay midfielder Marcelo Estigarribia was also on target as Sampdoria won 3-2 at promoted Pescara, who have lost all three games.
Edinson Cavani sent Napoli on their way with a second minute penalty and Goran Pandev added the second in the 39th minute, before Marco Parolo pulled one back just before the break.
Lorenzo Insigne made the game safe for Napoli in the 77th minute.
Roma stormed into a two-goal lead with goals from Alessandro Florenzi and Erik Lamela in the first 16 minutes but two goals in as many minutes from Alberto Gilardino and Alessandro Diamanti pulled Bologna level in the second half.
Gilardino then struck a last-minute winner to give Bologna their first points.
Udinese got off to an even quicker start as Dusan Basta and evergreen Antonio Di Natale scored in the first five minutes but Emanuele Calaio and Ze Eduardo levelled for Siena in the last 20 minutes.
And Fiorentina secured a 2-0 home win over Catania courtesy of goals either side of half-time from Stevan Jovetic and Luca Toni.