Germany midfielder Sami Khedira decided a tight game in the 66th minute.
Last year's runners-up Napoli beat Milan 4-2 with braces from Milik and Callejon to rise to joint fifth in the table on four points. Also fifth are AS Roma, third last term, who let Cagliari come from behind to secure a 2-2 draw in Sardinia.
Juve were joined in top spot by Genoa, 3-1 winners at Crotone, Sampdoria, 2-1 winners against Atalanta, and Sassuolo, who beat Pescara 2-1. (Ansa)