Lazio 0 Roma 2: Strootman and Nainggolan continue Giallorossi dominance
Roma beat Lazio 2-0 in a typically frantic derby to maintain their dominance in the fixture.
Having battled back from career-threatening knee injuries, Kevin Strootman pounced on an error from Lazio defender Wallace to put Roma on their way to victory midway through the second period at a half-full Stadio Olimpico - both club's 'ultra' fans remain unhappy at changes made to the stadium in an attempt to segregate unruly supporters.
The goal was followed by a bench-clearing melee that saw Lazio substitute Danilo Cataldi sent off and the mood among the home contingent darkened further when Radja Nainggolan drove home a second with 13 minutes to go.
The Giallorossi are now unbeaten in eight derby games - their best run for 12 years.
Victory for Roma sees them remain four points behind Serie A leaders Juventus, having taken second place in the table back from AC Milan after their victory earlier on Sunday, with Lazio missing out on the chance to leapfrog their city rivals.
Lazio captain Lucas Biglia crunched into Diego Perotti a few seconds from kick-off to set the tone for a chaotic opening period.
Ciro Immobile blasted two good opportunities over the crossbar as Lazio made the early running against Roma's new-look back three, which was happy to sit deep and soak up the hosts' attacks.
Eventually Luciano Spalletti's system began to click and a spell of Roma dominance resulted in a moment of high controversy.
Right wing-back Bruno Peres surged into the penalty area before slipping under the attention of Biglia, with referee Luca Banti pointing to the spot and issuing a booking to the Argentina international.
Lazio were incensed at the decision, prompting Banti to convene with his assistants on the line and behind the goal, before eventually overturning his decision and awarding a Roma free-kick outside the area, in turn angering the Giallorossi, who wasted the set-piece opportunity.
Federico Marchetti produced a stunning plunging save to deny Edin Dzeko just past the hour, but the Lazio goalkeeper was helpless when Wallace dithered in possession inside his own box, Strootman pouncing to rob him of the ball and dink a neat finish into the net.
After Strootman had taken to the running track to celebrate with the Roma fans, he was ambling his way back into his half before Cataldi yanked at his shirt and sparked a touchline scrap that resulted in his dismissal.
And before Lazio could carve out a comeback, they were dead and buried as Nainggolan was allowed to roam towards goal before blasting a 25-yard effort beyond a poorly positioned Marchetti.
A string of tetchy Lazio fouls gave the game a bitter aftertaste, but winning four derbies in sequence for the first time in five years will be sweet enough for Roma, whose players celebrated in front of a barren 'Curva' after Francesco Totti and Daniele De Rossi's please for the ultras to attend had been ignored.