|Milan's Ibrahimovic played an important part in an important victory over AC Roma [AFP]
Zlatan Ibrahimovic scored twice to lead AC Milan to a 3-2 win at Roma on Saturday, which saw the Serie A champion move provisionally to the top of the table.
"That's three fundamental points. We played really well and with a bit of luck it could have finished 4-1 or 5-1," said Ibrahimovic.
Napoli, who were level on points with Milan before kickoff, missed their chance to go top as they lost 2-1 at Catania.
Alessandro Nesta scored Milan's second, shortly after Nicolas Burdisso's equaliser, to help Massimiliano Allegri's side move a point clear of Juventus, who play Inter Milan later.
Bojan Krkic gave Roma brief hope when he scored three minutes from time.
Napoli got off to the perfect start when Ezequiel Lavezzi fired his team ahead with less than a minute on the clock, but Giovanni Marchese and Gonzalo Bergessio scored for Catania.
Napoli, who have never won at Catania in Serie A, saw Mario Santana sent off for a second yellow, three minutes from halftime.
At Roma, Allegri called the game a "direct battle for the title" and, knowing what was at stake, both teams started cautiously.
Milan, who had picked up just one win in their opening five league matches, took the lead in the 17th minute when Ibrahimovic leapt high in the area to head in Alberto Aquilani's cross.
Roma immediately upped the pressure and it paid off in the 28th minute as Burdisso headed in the equaliser from a corner.
However, Milan restored their advantage almost immediately when Nesta headed in almost an exact replica from Robinho's corner.
Milan had only won twice at the Stadio Olimpico in the past 14 years, but Ibrahimovic secured a third triumph in the 78th minute. Antonio Cassano picked out Aquilani on the edge of the area and he floated a pass towards the edge of the six-yard box, where the Sweden striker was waiting to head powerfully home.
Roma got back into the game three minutes from time when Milan goalkeeper Christian Abbiati could only parry a fierce shot from Erik Lamela and it fell into the path of Bojan to lash into the back of the net.
Worrying for Milan, however, was the sight of Kevin Prince Boateng limping off injured shortly after the hour mark.
| Catania's midfielder Gonzalo Bergessio celebrates scoring the winner against Napoli [AFP]
Soon afterwards Boateng was sent to the stands for protesting a decision, and Allegri was to follow him in injury time.
Napoli are back in fifth after a game they will want to forget at Catania.
Lavezzi put them in front almost straight from kick off when he beat his defender Nicolas Spolli to lash home Andrea Dossena's cross.
However, Catania drew level in the 25th minute when Alejandro Gomez's effort was deflected into the path of Marchese who fired in the equaliser.
Things went from bad to worse for the visiting side shortly before halftime when Santana received his marching orders with a second yellow card for bringing down Adrian Ricchiuti.
Catania scored what was to prove the winner three minutes after the break as Bergessio headed in a perfect cross from Ricchiuti.