(CNN) -- Sampdoria lost ground on Inter Milan at the top of Serie A on Sunday when they were held to a 1-1 draw at Lazio in a game where both teams finished with 10 men.
Lazio players celebrate Francesco Matuzalem's equalizer in the 1-1 draw against Sampdoria.
Champions Inter lead Sampdoria by two points having thrashed Genoa 5-0 on Saturday while Juventus and Fiorentina, who drew 1-1 in Turin, are a further two points behind.
Sampdoria needed a win to join Inter on 19 points at the top but despite taking the lead through Giampaolo Pazzini, they were pegged back by a goal from Francesco Matuzalem.
The visitors went in front on 40 minutes when Marco Padalino, who would later be sent off, crossed for Pazzini to head home.
But only two minutes later, Matuzalem latched onto Tommaso Rocchi's lobbed through ball to shoot across keeper Luca Castellazzi into the far corner.
Padalino was sent off 10 minutes in the second period but Roberto Baronio was then dismissed for Lazio on 73 minutes.
Cassano almost snatched victory for Sampdoria six minutes from time as his long range effort clipped the corner of post and crossbar.
On Saturday, Inter showed they are a forced to be reckoned with as they aim for a fifth straight Italian title with a comprehensive away win.
Goals from Esteban Cambiasso, Mario Balotelli and a stunning volley from the halfway line from Dejan Stankovic had Inter in control at the break before Patrick Vieira and Maicon wrapped things up.
In other Sunday matches, Ronaldinho inspired AC Milan to only their third win of the season with a come-from-behind 2-1 success over Roma at the San Siro.
The result moved Milan up to eighth in the table with Roma dropping to 11th.
Roma took a third minute lead when French winger Jeremy Menez pounced on Thiago Silva's fluffed back-pass and shrugged off the Brazilian's shirt-pulling before sending goalkeeper Dida the wrong way.
Milan levelled in the 56th minute when Alessando Nesta tumbled under Nicolas Burdisso's challenge in the box and Ronaldinho despatched the penalty.
The winner came 11 minutes later when Ronaldinho's long diagonal ball found Alexander Pato, who controlled the ball superbly on his chest before slotting home.
Meanwhile, Parma moved up to fifth after Bulgarian forward Valeri Bojinov scored the only goal of the game at home to Siena.
Walter Mazzarri's first game in charge of Napoli ended in victory after Cristian Maggio struck in injury time to sink Bologna 2-1.
Catania and Atalanta recorded their first victories of the season, 2-1 at home to Cagliari and 3-1 at Udinese.