Suspended Roma coach Jose Mourinho clashed with Lazio president Claudio Lotito after defeat on Sunday.
Mattia Zaccagni struck the winner for Lazio as three players saw red.
Afterwards, Mourinho clashed with Lotito as tensions boiled over in the dressing rooms.
Gazzetta dello Sport says it began when Alessio Romagnoli celebrated in front of Roma's dressing room, causing Gianluca Mancini's reaction. The latter reportedly left the room, calling his compatriot a 'piece of s…'.
Lotito pushed them apart, but Mourinho was also on the spot despite serving the second of a two-match ban. Roma sources say a FIGC commissioner had authorised him to be inside the dressing room after the game.
“What are you looking at?" Mourinho reportedly told Lotito.
“I am the Lazio President," Lotito replied. “Who are you? This is my home and you shouldn't even be here."
Roma director Tiago Pinto had to intervene to divide them while Luis Alberto and Mourinho's assistant Salvatore Foti also clashed.