Lazio's Scudetto challenge suffered a setback as they were beaten at home by Chievo.
Alberto Paloschi sealed a smash and grab win for the Flying Donkeys, who needed just one sight of goal to snatch the points against a wasteful, and slightly off-colour, Lazio.
The home side had the better of the game without really testing Christian Puggioni in the Chievo goal enough to warrant more than what they got.
Lazio coach Vladimir Petkovic took a gamble in leaving Hernanes and Stefano Mauri out of his starting XI, but perhaps in doing so, he underestimated the threat of the opposition.
Lazio played with the same attacking style which distinguishes them, but they were lacking something in front of their midfield, where Hernanes and Mauri usually lurk.
Full-back Abdoulay Konko had their first shot on goal in the 23rd minute, but Chievo goalkeeper Puggioni did not even need to move to save it.
Likewise in the 53rd minute, Puggioni just had to stand still and punch Sergio Floccari's effort wide.
Mauri was on the pitch at this stage, and Lazio were showing signs of improvement.
In the 59th minute, the man who scored Lazio's equaliser in the Coppa Italia against Juventus was uncharacteristically wayward with a header from seven yards out after he found room between two Chievo defenders.
Two minutes later, Chievo surged forwards to take the lead with their first chance of the game.
Cyril Thereau got to the goal line and pulled the ball back for Vacek, who was only on the field due to an injury to Gennaro Sardo. His shot struck the underside of the crossbar and fell to Paloschi, who slotted it in from close range.
Hernanes was also on the field now, and Libor Kozak was sent on too as Petkovic tried to rescue the game.
Another defender, Andre Dias, had their next chance, but he followed the tradition of shooting straight at Puggioni, who could have been a statue and would have still kept out Lazio's three shots on goal.
Lazio did not seem to want to score, or at least Floccari did not when he passed up the chance to shoot from 10 yards in a central position to tee up Mauri to his left, and his shot from an angle cleared the crossbar in the 76th minute.
Lazio tried to salvage a point, but nearly conceded a second in the last minute when Seymour was denied by Federico Marchetti at his near post.