MILAN — Zlatan Ibrahimovic scored with an early penalty Sunday to give AC Milan a 1-0 win against former team Inter Milan and end a run of three losses in the Serie A derby.

The Sweden forward converted his spot kick past goalkeeper Luca Castelazzi in the fifth minute at the San Siro after he was brought down by Marco Materazzi. It was Ibrahimovic's first Milan derby since leaving Inter for Barcelona in 2009.

Milan leads the standings with 26 points, one more than Lazio. Napoli is third with 21, and Juventus and Inter have 20 points.

"It wasn't an easy goal as it was in front of the Inter fans at their home game, but I did what I had to do and tried to concentrate," Ibrahimovic said. "I think it gave the team confidence and we became more calm and it helped us win.

"I am always confident in the teams I play for and it is fair that we are favorite. But there is also Inter, Juventus and AS Roma is playing well and improving, but with patience we can finish top."

Milan fullback Ignazio Abate was sent off in the 60th minute after collecting a second yellow card.

Also Sunday, Lazio beat Napoli 2-0 through goals from Mauro Zarate and Sergio Floccari and Bologna downed Brescia 1-0 and Genoa won 1-0 at Cagliari.

Milan midfielder Clarence Seedorf headed over Abate's cross from close range in the second minute in a bright start for the Rossoneri.

Milan continued to dominate after the goal. Ibrahimovic set up Mathieu Flamini, but Inter defender Javier Zanetti got back in time to stop him shooting.

Eventually, Inter coach Rafael Benitez changed his system and brought on Coutinho to help Samuel Eto'o and Diego Milito in attack. It nearly had an immediate impact as the young Brazilian shot wide after combining with Eto'o and Wesley Sneijder.

Sneijder curled a free kick into the side-netting in the 38th. After halftime, another free kick by the Dutchman forced goalkeeper Christian Abbiati into a sprawling save.

Milan went down to 10 men when Abate received his second yellow card after clashing with Goran Pandev, but Milan came the closest to scoring despite being a man down.

"It was a tricky situation and it was a pity he had that reaction," Milan coach Massimo Allegri said. "But his sending off meant we focused more."

Materazzi was later carried off and taken to a hospital after the Inter defender injured a cheekbone in a collision with Ibrahimovic.

"I heard that he's OK, but I'm sorry that he was hurt," Ibrahimovic said. "It was a 50-50 ball and we both went in hard. I'm not sure what happened, but the important thing is that he's OK."

Andrea Pirlo and Ibrahimovic combined to set up Seedorf for a shot that flashed just past the post.

Benitez brought on winger Jonathan Biabiany to add some more pace to the attack, but it was not enough against a determined Milan side.

"I said before that it would be an important match, but the season is long," Benitez said. "We have to win more to get up with Milan, but we have had injuries against Lecce and Brescia and we should have four points more. But we have to work hard from now on and go for three points every match."

Lazio lost the Serie A league leadership after losing its last two matches, but was in control throughout the game. Zarate opened the scoring in the 15th minute, and Floccari doubled the lead from Zarate's pass in the 61st.

Napoli's best chance came in the first half when Ezequiel Lavezzi hit the bar. Edinson Cavani missed a late chance after Lazio goalkeeper Fernando Muslera spilled the ball into his path.

"We trust in our quality and know what we are capable of," Floccari said. "It has been a tough three days and a with the midweek loss it made it a bad week for us. We knew that this would be a tough game."

Antonio Di Natale hit a first-half hat trick to help Udinese to a 4-0 win over Lecce, with Antonio Floro Flores scoring Udinese's fourth after halftime.

Javier Pastore also found the net three times as Palermo beat Catania 3-1 in the Sicilian derby.

Sampdoria's problems in front of goal continued, with the Genoa-based club drawing 0-0 at home to Chievo Verona. The side has scored only one goal in four games since the club suspended striker Antonio Cassano.

Bari remains bottom of the standings after losing 1-0 to Parma, with Andrea Candreva scoring the winner. Alessandro Parisi missed a penalty for Bari in the first half and Massimo Donati was sent off late for a second yellow card.

Lazio captain Stefano Mauri set up Zarate to score the opening goal. He played the Argentine in behind the Napoli defense and Zarate clipped the ball past Napoli goalkeeper Morgan De Sanctis.

Lavezzi jinked inside the Lazio defense in the 29th and curled a shot past Muselera, but it came back off the bar.

De Sanctis stopped Zarate from doubling his tally in the 33rd and then blocked Stephan Lichsteiner's shot at the near post after the fullback had escaped from Gianluca Grava.

Lichsteiner and Cristian Ledesma both had shots before Floccari added a second for Lazio.

The ball ran free in the Napoli area, Zarate was first to it and he slipped the ball to Floccari for his strike partner to sidefoot past De Sanctis.

"The game was good and my goal came at a good time as it meant we handled the game in the right way," Floccari said. "Napoli made us work hard, but we handled the match well in the second half and finished the match in the right way."

Zarate went close to scoring twice more. First De Sanctis tipped his shot wide and then the ball deflected off Paolo Cannavaro and off the bar.

"Today was a good performance in terms of the intensity and our creativity in attack," Floccari said. "It is always good to score, but it was better that we played well."