The Brazilian winger was seen intentionally spitting in the direction of Federico Di Francesco's face.
Five-time Ballon d'Or victor Ronaldo, who arrived amid great pomp and ceremony following a 100-million-euro deal from Real Madrid, tapped in from barely a yard out after a goalmouth scramble on 50 minutes.
"I wanted to score, I'm really happy", said Ronaldo, who had missed several good chances in previous games. "Obviously, I felt I deserved to start the game", said Bale.
Then the other team gets back into the game, some players get irritated and that sort of thing happens.
Sassuolo pulled one back in added time via Khouma Babacar but Juve held on.
He will now look to end Juventus' 22-year wait for Champions League glory, and the five-time Ballon d'Or victor is eager to return to the competition where he has scored a record 120 goals.
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It also boasts a modest $55 million price tag, which is significantly lower than most other tentpole flicks in the genre. And (spoiler alert) his caption simply stated the Joker's real first name: "Arthur".
Juventus have won their first four Serie A games and will now turn their attention to their first Champions League group-stage game, which will be away against Valencia on Wednesday.
The Portugal forward had scored his first league goal in his fourth match last season for Real Madrid. "It's a very hard group, we know that we can do well and Juve must focus on being the best".
Madrid's all-time top goalscorer Ronaldo was crucial to the club's three consecutive Champions League wins under former coach Zinedine Zidane, although it was Bale who scored twice against Liverpool in the 3-1 triumph in May's Kiev final.
Stephan El Shaarawy and Bryan Cristante put Roma, who lost to AC Milan before the global break, firmly in command at half-time.
His barren run had stretched beyond the 300-minute mark during a goalless first-half at the Allianz Stadium, but he did not have to wait long to make his mark after the interval.
But Valter Birsa reduced the deficit shortly after the break with a magnificent curled strike and Chievo equalized seven minutes from time when Mariusz Stepinski fired in a rebound. "I think he deserves it", said Allegri. "We mustn't lose our heads, even if these results destabilise us".