كتب : Ahmad Saied
Roberto Mancini's side have 14 points on top while Roma come second two points behind.
In Milan, Giuseppe Mascara fired Catania into a surprise lead when he dinked a great shot home from outside the area in the 16th minute.
But a superb performance from veteran midfielder Dejan Stankovic helped Inter clinch the three points.
He equalized in the 29th minute before finding the net again in the 79th minute to seal the win.
Julio Cruz could have extended the lead but he failed to score from the spot.
In another match, title challengers Roma slumped to a shocking 1-0 defeat against Reggina.
Nicola Amoruso struck the winner home from inside the area four minutes into the second-half.