Thiago Motta must have been demanding a response from his players who were thumped 4-0 by Atalanta a week ago, but there were no signs of recovery from the Bianconeri in the opening stages here.
Juve struggled to move the ball on a playing surface that had absorbed plenty of rain in recent days, but the hosts had no such issues as they scored twice in the space of three minutes to surge clear.
First, Robin Gosens volleyed home after his header from a corner was blocked, before Rolando Mandragora swept home a sumptuous finish from outside the box having been found by Nicolo Fagioli.
Juventus were shellshocked, and never really recovered before the interval as they failed to register a single shot on target despite dominating possession.
Nothing really changed for the better after the restart for the visitors, who were soon three behind and out of the contest altogether.
Once more, a desperate lack of intensity in their defending cost the Old Lady dearly, as Albert Gudmundsson was allowed to drive towards the box unmarked and unleash a fearsome strike that nestled in the far corner.
The visitors’ lack of attacking threat made Motta’s decision to leave Dusan Vlahovic out of the starting XI - and keep him on the bench throughout - even more baffling.
The Juve boss now finds himself under serious pressure for his position after a second successive loss without scoring, which leaves his side outside of the top four.
Fiorentina take the plaudits with a much-needed win, just their second in six league matches, to close in on the European places.
Flashscore Man of the Match: Nicolo Fagioli (Fiorentina)