Ivan Perisic fired the champions in front from the penalty spot early on, but Ciro Immobile equalised with a spot kick of his own midway through the second half.
Lazio went in front on the 81st minute when Felipe Anderson tucked in a rebound from close range, but the goal incensed the Inter players as Nerazzurri wing-back Federico Dimarco was down injured when the hosts launched the counter-attack leading to the goal.
But Sergej Milinkovic-Savic made sure of victory with a close-range header in stoppage time as the Aquile stretched their unbeaten home league run to 17 matches. Lazio’s Luiz Felipe was sent off after full-time as the scuffles continued, but the result sees Maurizio Sarri’s side move up to fifth place on 14 points, three behind third-placed Inter.
Reina 6.5; Marusic 6, Felipe 6, Patric 6.5; Hysaj 5.5 (Lazzari 6.5); Milinkovic-Savic 7, Lucas 6.5 (Cataldi 6), Basic 6 (Luis Alberto 6.5); Anderson 8 (Akpa Akpro 6), Immobile 7, Pedro 7 (Zaccagni 6)
LAZIO PLAYER OF THE MATCH: FELIPE ANDERSON
Maurizio Sarri believes the Brazilian is one of the most naturally gifted players he’s worked with, and nights like this remind you why. The winger was Lazio’s greatest threat throughout the first half and deserved his goal when it eventually came. When he’s in this kind of form, displaying pace, dribbling and technique, he’s hard to stop.