Sassuolo came back from a Mattia Zaccagni opener to beat Lazio 2-1 with Domenico Berardi and Giacomo Raspadori, but they were rescued by the woodwork in stoppages.
The Neroverdi had already caused a few upsets this season, beating Milan and Juventus while holding Napoli to a 2-2 draw. Maurizio Sarri had to completely revamp his midfield, as Sergej Milinkovic-Savic was suspended and Luis Alberto injured.
Lazio took the surprise lead early on, as Elseid Hysaj won it back in midfield, sent Pedro down the right, the pull-back finding Mattia Zaccagni to score from 10 yards. Curiously, Zaccagni had also scored against Sassuolo when playing for Verona in August, so beat the same opponents with two different clubs in the same season.
Gianluca Scamacca fought back, his turn and shot fingertipped out of the near bottom corner by Thomas Strakosha, while Giacomo Raspadori had an effort charged down.
Strakosha palmed another Scamacca strike onto the far post after a Davide Frattesi counter-attack, then had his gloves stung by Frattesi from distance.
Straight after the restart, Domenico Berardi failed to make the most of a defensive error, firing over the bar.
Berardi did get his equaliser eventually, cutting inside and finding the tiny gap between Lazio bodies to curl left-footed into the far top corner from the edge of the area.
It was increasingly just Sassuolo and they turned it around completely with a very similar goal. Berardi made the same run from right to left on the cusp of the box, but this time Raspadori fired in the finish.
There was a tense finale, as Kaan Ayhan pulled Vedat Muriqi back just outside the area and received a red card for the last man foul.
On the resulting free kick, Toma Basic unleashed a rocket that smacked against the crossbar with Consigli beaten.
Sassuolo 2-1 Lazio
Zaccagni 7 (L), Berardi 63 (S), Raspadori 69 (S)
Sent off: Ayhan 87 (S)