Former leaders Napoli had fallen four points behind Juventus and Gonzalo Higuain's equaliser - his first goal in five matches cancelled out Marcos Alonso's early header for Fiorentina - was only enough to reduce the gap to three points on Monday night.
La Viola, meanwhile, draw level on points with Roma in the final Champions League place, but remain fourth due to an inferior head-to-head record.
Earlier, Sassuolo underlined their European credentials by surprising Lazio 2-0 at the Stadio Olimpico.
The Neroverde, who only arrived in the top flight three years ago, claimed all three points in the capital city thanks to Domenico Berardi's penalty and a second-half rocket from Gregoire Defrel.
Eusebio Di Francesco's men are now six points behind AC Milan and the nearest Europa League berth.
