Fiorentina inflicted a first defeat of the season on Roma as a late goal from Milan Badelj secured a narrow 1-0 win at Stadio Artemio Franchi on Sunday.
It was a controversial winner, however, with Badelj's shot going through the legs of La Viola team-mate Nikola Kalinic, who was one of three players standing offside, on its way past Wojciech Szczesny.
The Giallorossi looked dangerous in the first half, particularly Edin Dzeko, who created numerous chances. The Bosnian striker sent a header just over the crossbar from Alessandro Fiorenzi's ball in before firing a volley straight at Ciprian Tatarusanu in the home goal.
Dzeko was then denied a penalty when he went down in a clash with Nenad Tomovic, while he should have done better after being played in by Fiorenzi, but failed to hit the target.
The hosts hadn't offered much in attack but they finished the half strongly, with Josip Ilicic and Borja Valero presented with opportunities to score, although neither shot required saving from Szczesny.
Kalinic spurned a glorious chance to break the deadlock in the second half when he steered a weak header straight at Szczesny from Federico Bernardeschi's cross, while at the other end Tatarusanu had to be alert to tip Florenzi venomous strike over the bar.
The opener finally arrived on 82 minutes, although it was contentious to say the least as the referee allowed Badelj's effort to stand, despite a question of offside surrounding the goal.
Francesco Totti almost came to the visitors' rescue at the death with a shot from outside the area that sailed just to the left of the goal as Luciano Spalletti's side suffered their first loss in the new Serie A campaign.