It took the Portuguese forward almost 320 minutes to score his first league goal for Juve and he did it with the simplest of tap-ins.
"I expect nothing more, and nothing less than what he did in the first three games".
The Portuguese star Ronaldo scored 451 goals in 438 games with Real Madrid, including a record 120 in Champions League play.
The 33-year-old tapped in on the line after a goalmouth scramble on 50 minutes and added a second 15 minutes later to give the reigning seven-time champions a 2-0 lead.
Juve midfielder Douglas Costa was sent off in stoppage time after spitting at Federico Di Francesco having become involved in a running feud with the Sassuolo midfielder.
The visitors set up a nervous final few minutes when Khouma Babacar nodded home from close range, while Douglas Costa was sent off for an off-the-ball incident.