Inzaghi , who had not found the net in five games, claimed opportunist goals in the 34th and 59th minutes as Juve made light of the absence of both their suspended French playmaker Zinedine Zidane and Edgar Davids, of the Netherlands.
Victory was enough to put the reigning champions a point ahead of Fiorentina, who have set the Serie A pace since the opening day of the season but slipped to a 2-0 defeat at Parma on Saturday.
Unlike Fiorentina, Internazionale started the season expecting to win the title, but last year's runners-up dropped deep into crisis after a dramatic 3-2 home defeat to Bari in which the Portuguese midfielder Paulo Sousa was sent-off.
A third successive league defeat drops the pre-season title favourites to eighth place, six points adrift of Juventus. "The next two matches - against Spartak Moscow in the Champions' League on Wednesday and Milan next Sunday - will be decisive," warned Inter's president Massimo Moratti, laying down an ultimatum to his coach, Luigi Simoni.
"I have certainly made more mistakes than anyone else," Simoni said, "but everyone must assume their responsibilities. President Moratti must make his decision with calmness. I'm sorry. I am failing to satisfy both him and the fans."
In the Spanish League, Real Madrid extending their 100 percent away record this season with a 5-1 win at Extremadura. Barcelona came from behind to beat Real Sociedad 4-1, with two goals apiece from the Brazilian pair of Rivaldo and Sonny Anderson.
In Germany, Bayern Munich slumped to their first Bundesliga defeat of the season when they had Carsten Jancker sent off and lost 1-0 at promoted Eintracht Frankfurt.