Argentine striker Hernan Crespo put the reigning champions ahead with an angled header and Serbian midfielder Dejan Stankovic's driven shot from outside the box gave Inter a two-goal half-time lead.

Swedish striker Zlatan Ibrahimovic increased Inter's advantage shortly after half time at the San Siro, only for Clarence Seedorf to quickly pull one back for Milan.

Marco Materazzi's celebrations after he had headed home Inter's fourth goal earned him a second yellow card and an early bath.

His dismissal sparked a rousing fightback by Milan whose morale had been damaged 24 hours earlier by their failure to see an eight-point penalty for match-fixing overturned on appeal.

Alberto Gilardino headed his first goal for six months before Kaka's lob in the first minute of five minutes of stoppage time ensured a nail-biting finale, but Inter's 10 men held on.

Six wins from their nine matches played left Inter on 21 points, three ahead of Palermo who visit Fiorentina on Sunday. Roma are third on 17 points after their 1-0 win at Udinese in Saturday's early match.

AC Milan remain on seven points.

Inter, who finished third last season but were awarded the title after Juventus and AC Milan were found guilty of rigging matches in the 2004-05 season, started aggressively and they went ahead in the 17th minute.

Stankovic delivered a free-kick into the penalty box, and Crespo jumped above Marek Juankulovski to plant a firm header wide of Nelson Dida's outstretched hand for his fourth goal of the campaign.

Worse was to follow for the six-time European champions five minutes later.

Maicon burst down the right and fed Stankovic who took one touch before firing a right-footed screamer into the top corner from 22 yards for his fourth goal of the season.

Ibrahimovic rounded off a quick counter-attack prompted by Stankovic at the start of the second half, but Milan responded when Seedorf's heavily-deflected shot looped past Julio Cesar.

Materazzi stole in at the back post to head home Stankovic's cross in the 68th minute, but he was then immediately ordered off for pulling off his shirt.

Substitute Gilardino's glanced in Cafu's cross 15 minutes from time before Kaka's cheeky effort set the alarm bells ringing for Inter.

In Saturday's early match Roma returned to winning ways at Udinese.

Central defender Matteo Ferrari scored the only goal in the 66th minute to become the 12th Roma player to find the net in the league this season.

Udinese were reduced to 10 men four minutes later when their Ghanaian midfielder Sulley Muntari was sent off.

Victory for Roma revived their title challenge after a defeat and two draws.

Udinese, who have taken just two points from their last three matches, remain on 13 points.