Lazio came from behind to beat Roma 3-2 in a rain-drenched Serie A derby in Rome on Sunday in which both teams were reduced to 10 men.
Erik Lamela gave Roma a controversial lead in the ninth minute, but goalkeeper Mauro Goicoechea allowed Antonio Candreva's equalizer to slip through his hands.
Miroslav Klose fired Lazio in front before Roma midfielder Daniele De Rossi was sent off in first-half stoppage time for punching Stefano Mauri in the face.
A defensive howler from Roma right back Ivan Piris allowed Mauri to make it 3-1 to Lazio.
In a dramatic finale, Mauri was sent off before substitute Miralem Pjanic pulled one back for Roma. However, Lazio clung on for its third successive derby victory.
"I'm disappointed with De Rossi's actions," Roma coach Zdenek Zeman said. "We talked for two days about those risks, that you didn't need to react or give in to provocation. Of course emotions are high in the derby, but when you feel it too much you pay.
"I haven't talked to De Rossi yet. He went to jump, was held back and reacted that way. What else is there to add? I'm disappointed for him and the team, we'll have to play the next games without him."
De Rossi apologized to Mauri but is likely to be dropped from the Italy squad to face France.
In Atalanta, Inter Milan's 10-game winning run in all competitions was ended Sunday with a 3-2 loss.
After ending Juventus' 49-game unbeaten run in Serie A last weekend, Inter has slipped four points behind the leader and defending champion. It is also only a point ahead of Napoli.
Elsewhere, AC Milan missed a penalty in losing 3-1 against Fiorentina, and Napoli came from behind to beat Genoa 4-2.
In Rome, there were tributes before the match to Gabriele Sandri, the Lazio fan killed by a stray police bullet five years ago. Tensions were high and a Roma fan was stabbed outside the stadium before kickoff as trouble threatened to flare, with objects — including a Molotov cocktail — thrown across the heavy police cordon separating the rival fans.
On the pitch, play had to be halted for a few minutes as the floodlights failed.
When it did resume, Lamela headed in Francesco Totti's corner for his seventh goal in six games. Lazio players called for the goal to be disallowed for a push by Lamela on Senad Lulic.
Lazio levelled in the 35th with a stunning long-range free-kick from Candreva which slipped through Goicoechea's hands and took the lead when Klose slotted in Hernanes' through ball.
Matters got worse for Roma minutes later as De Rossi became the 13th player to be sent off in nine matches between the two.
Lazio extended its lead immediately after the break as Roma's Piris headed an innocuous-looking long ball straight to Mauri on the edge of the area and the Lazio striker smashed it in.
Lazio seemed to be heading for a comfortable victory before Mauri got a second yellow card for handball. Pjanic scored moments later with a free kick from 30 metres after spotting Lazio goalkeeper Federico Marchetti off his line.
Roma almost levelled deep in stoppage time after a fantastic pass from Michael Bradley which Pablo Osvaldo fired wide.
Milan was jeered off the pitch at halftime and fulltime after losing at home to Fiorentina.
"We lost against a good Fiorentina side but we gifted them two goals in an important game which could have lifted us up to sixth place," Milan coach Massimiliano Allegri said. "Fiorentina played well but we didn't react after the goals and that's not right.
"In general I think this squad is doing its utmost, we've paid a lot for mistakes we've made, the players we have are growing. This is a squad that has to always play a thousand miles an hour because of the players' characteristics and talents, but you can't do that playing every three days and there are games in which you must play worse but still look to win."
Former Milan midfielder Alberto Aquilani gave Fiorentina the lead in the 10th minute but the home side should have levelled from the penalty spot after Alexandre Pato was bundled over by Facundo Roncaglia.
However, Pato blazed his spot kick way over the crossbar.
Minutes later Borja Valero scored his first goal for Fiorentina after sailing past Riccardo Montolivo and evading a poor challenge by Philippe Mexes.
Mexes redeemed himself on the hour mark with a backheel which bounced off the right post and straight to substitute Giampaolo Pazzini for an easy tap-in for the former Fiorentina star.
Milan threw everything forward but Mounir El Hamdaoui sealed the match two minutes from time with an impressive diagonal shot into the top right corner.
There were fears Napoli's game would be postponed with Genoa on lockdown amid flood warnings, following knock on effects from Hurricane Sandy.
Genoa, which had lost all three games under Luigi Del Neri, was twice in front through Ciro Immobile and Luca Antonelli. Former Genoa defender Giandomenico Mesto and Edinson Cavani — who scored four midweek — levelled before Marek Hamsik and Lorenzo Insigne turned the match around.
In the lunchtime fixture, Palermo beat fellow strugglers Sampdoria 2-0 with teenager Paulo Dybala notching his first goals in Serie A.
The loss is Sampdoria's seventh successive defeat and threatens to spell the end for coach Ciro Ferrara's brief time in charge.
Elsewhere, Gabriele Angella scored twice to help Udinese draw 2-2 at Chievo Verona. The defender also had a goal wrongly disallowed for offside.
Marco Andreolli had given Chievo the lead and Alberto Paloschi restored its advantage from the spot in his first game back after a lengthy injury layoff.
Chievo's Luciano had thumped an earlier penalty off the crossbar. Danilo was sent off late on after receiving two yellow cards for giving away both penalties.
Torino picked up its first victory in six games with a 1-0 win over Bologna, while Parma drew 0-0 at home to Siena.