Stefano Mauri's second-half strike saw Lazio defeat a 10-man Roma 2-1 in Sunday's Serie A action.
Roma made a terrible start to the derby as they were reduced to 10 men after just nine minutes.
Goalkeeper Maarten Stekelenburg was the man to receive his marching orders after he fouled Miroslav Klose in the penalty area.
The resultant spot-kick was tucked away by Hernanes and Roma faced an uphill battle.
They managed a quick equaliser though as forward Fabio Borini scored after 16 minutes.
The scoreline remained the same until half-time, before Lazio took the lead for a second time through Mauri on 62 minutes.
And despite having defender Lionel Scaloni sent off for a second yellow card in the dying stages, Lazio held on for all three points.
In other matches, Napoli beat Parma 2-1 thanks to Ezequiel Lavezzi's late winner.
Cristian Zaccardo cancelled out Edinson Cavani's opener with 13 minutes left but Lavezzi had the last laugh on 86 minutes.
Udinese drew 0-0 with Atlanta, Siena thumped Cagliari 3-0 and Fiorentina defeated bottom-placed Cesena 2-0.
The day's other match saw Genoa's Giuseppe Sculli score twice to give his side a point in an entertaining 2-2 draw at Lecce.
Bologna stole a late 1-0 victory over Novara to leap three points clear of the drop zone, in which the losers sit - 11 points from safety.
In the late kick-off, Inter Milan fought back from a two-goal deficit at home to earn a 2-2 draw with Catania.
Alejandro Gomez and Mariano Izco had the visitors two goals to the good in the opening half, before two second-half strikes eight minutes apart from Diego Forlan and Diego Milito saw the San Siro side earn a point.