
Inter came close to losing their first game this season as Parma came from behind to lead 2-1 with 22 minutes left.
They lead now on 49 points from 19 games at mid-season, with Roma on 42 after beating Catania 2-0 earlier Sunday. Meanwhile, 37-point Juventus were held to a scoreless draw at home to Sampdoria.
At the foggy Giuseppe Meazza, Inter failed to threaten early in the game and ran a couple of risks on Parma's 21st-minute hammering attack with shots from Brazilian Reginaldo and Daniele Dessena blocked by defenders.
Four minutes later, Brazil goalkeeper Julio Cesar offered Parma another chance as he failed to hold onto a harmless cross, before Zlatan Ibrahimovic fired a low drive posing no threat for Luca Bucci.
The veteran Parma custodian was helpless on 30 minutes as Argentinian Esteban Cambiasso slammed home a loose ball following a corner kick from the right.
Parma often lacked precision in their attacks but on 40 minutes constructed a good action on the right flank, whence Reginaldo squared for the young Luca Cigarini, who drilled a precise drive by the far post.
The guests kept showing no respect after the break and missed a chance on 58 minutes as Reginaldo selfishly squandered a counterattack, refusing to offer the ball to his striking mate Bernardo Corradi.
Brazilian substitute Cesar fired high for Inter, but Parma came close again on 65 minutes with a great drive from Andrea Pisanu that Julio Cesar deflected before Fernando Couto nodded the ensuing corner kick against the post.
Parma's lead on 68 minutes came from a swerving free kick fired by substitute Andrea Gasbarroni from the left flank of the area, which was aided by a minute deflection by a defender and surprised Julio Cesar.
With 15 minutes to go, Cambiasso came close again with a header that Bucci denied with a great dive that preceded the hosts' equalizer through a highly controversial spot kick. Ibrahimovic converted with three minutes left after the linesman called a handball from Fernando Couto, who appeared to have headed the ball off the goal line.
With Fernando Couto dismissed for his foul and Parma unable to replace the injured Dessena, Ibrahimovic scored the winner, controlling a cross with his chest and firing home to become the league top scorer, level with Juventus' David Trezeguet on 13 goals.
"Parma played very well," Ibra said. "They are very strong and should be higher in the standings (than their 18 points)."
By Alberto Cagliano, dpa