Adem Ljajic and substitute Luca Toni struck for the Viola, as Cristian Ledesma and Hernanes both saw red in the second half. The result sees Fiorentina rise up to fifth in the table, just three points behind Lazio.
Fiorentina nearly opened the scoring on 21 minutes, but Albano Bizzarri performed superman heroics to fly across goal to palm clear a Manuel Pasqual free kick. The Lazio stopper put his team before his own wellbeing though, as in making the save he clattered into the upright at speed.
Minutes later, Pasqual won a penalty when Abdoulay Konko tripped him. Matias Fernandez stepped up and struck the upright. The home support could sense a goal was coming and it did do in first half stoppage time. Ljajic picked up the ball on the edge of the box and expertly turned two defenders before unleashing an unstoppable shot into the top corner. It was no more than the hosts deserved after putting Lazio under the kosh.
The visitors fought back early in the second half. Miroslav Klose picked out Antonio Candreva in the box, who headed straight at Emiliano Viviano. In truth, he should have made the keeper work harder.
Klose then played a neat one-two with Hernanes and side-footed wide when it was easier to score.
On 73 minutes, Stevan Jovetic went down under Giuseppe Biava in the box. Play was waved on and Toni couldn't get enough on a header to turn it in. The ball came back to the veteran, but he stabbed it over.
The visitors then lost their discipline and self destructed. With 15 minutes to go, Ledesma picked up a second caution for a foul on Cuadrado. Despite a lengthy protest, the dismissal stood.
Seven minutes later, Hernanes was shown a straight red for a scissors on Cuadrado. Fearing the visitors would single him out some more, Cuadrado was withdrawn for Alberto Aquilani.
Biava headed off the line in the final minute to deny Toni, but the attacker got his revenge just moments later. Aquilani put in a low cross and Toni rolled back the years, when he spun past Biava to hit a shot on the turn which finished in the bottom corner.
Substitute Libor Kozak crossed for Klose to balloon over the final chance to compound a miserable afternoon for the visitors.
Fiorentina: Viviano; Savic, Rodriguez, Tomovic; Cuadrado, (Aquilani 85) Fernandez, (Migliaccio 62) Olivera, Borja Valero, Pasqual; Ljajic, (Toni 67) Jovetic
Lazio: Bizzarri; Konko, Biava, Dias, Lulic; Candreva, (Kozak 88) Gonzalez, (Rocchi 78) Ledesma, Hernanes, Mauri; (Brocchi 78) Klose