Lazio clinched a dramatic 3-1 victory over Serie A high-flyers Fiorentina on Saturday while cross-city rivals Roma were held to a frustrating 1-1 draw by AC Milan at the Stadio Olimpico.
With Inter, Napoli and Juventus all in action on Sunday, fellow title chasers Fiorentina had the chance to apply some pressure at the Stadio Artemi Franchi, only to fall behind on the stroke of half-time to Balde Keita's well-taken strike.
Sergej Milinkovic-Savic doubled the lead with a calm finish in the final minute of normal time but the drama continued in Florence as Etrit Berisha allowed Facundo Roncaglio's effort to slip through his hands.
Felipe Anderson - a reported target of Manchester United - rounded off the scoring with less than a minute of added time to play - capping a hectic finale that sees Paulo Sousa's men slip to third.
Back in Rome, Rudi Garcia went head-to-head with another under-fire boss as Sinisa Mihajlovic's Milan sought to end their mixed recent form.
Both sides have struggled for results of late but the hosts - who saw club legend Francesco Totti return from injury after a three-month absence - made a strong start when Antonio Rudiger opened the scoring four minutes in.
The frustration was audible from sections of the home support who could see their side fall further off the pace when the remainder of the league's leading pack play on Sunday.
The day's early game saw Udinese's inconsistent form continue in a 2-1 defeat to struggling Carpi - the hosts picking up just their third league win of the season at the Stadio Alberto Braglia thanks to goals from Lorenzo Pasciuti and Lorenzo Lollo.
