Mourinho is unpopular among Juventus fans after managing bitter rival Inter Milan for three years.
Their wins nicely set up a Manchester derby game in the Premier League on Sunday.
Ronaldo may not have found the net for Juventus in the 3-1 win over Cagliari, but the Portugal international has helped his new club win 10 of its opening 11 league games.
Ronaldo, who plays for Italian club Juventus and Portugal's national soccer team, has continued to play soccer amid the allegation.
Ronaldo scored twice as Juventus came from behind to win at relegation-threatened Empoli 2-1 on Saturday and maintain their unbeaten start in Serie A.
The defeat against Juventus leaves United with just one win from its last seven games as Mourinho's men struggle to make much headway on the roads or on the field.
Juventus delivered a powerful performance that extended its unbeaten start to the season to 11 games.
The football superstar has been accused of rape in the United States. Kathryn Mayorga filed a civil lawsuit last month in Nevada claiming Ronaldo raped her in his Las Vegas hotel room.
Barcelona hasn't won in four straight league games, while Madrid is winless in four matches in all competitions.
Zidane stepped down as coach after leading the club to three consecutive Champions League titles, while Ronaldo ended his nine-year association with Madrid when he joined Juventus.
Ronaldo hasn't been called up for the national team since the World Cup, and the Portuguese soccer federation has already said he also will not be considered for upcoming international matches later this year.
Ronaldo scored Juventus' second goal in a 2-0 win at Udinese to extend the Bianconeri's perfect start in Serie A.
Ronaldo, going by media reports, recently spoke to Santos and to Portuguese federation president Fernando Gomes, saying it is best for the 33-year old to not play for the country through November.
The 33-year-old Ronaldo has been accused of rape by an American woman. She has said the soccer great raped her in Las Vegas in 2009.
With Ronaldo watching from the stands after getting his first red card in the previous match, Dybala rediscovered the scoring form that saw the Argentina international score 22 Serie A goals last season.
Ronaldo set up all three of his side's goals — two for Mario Mandzukic and one for Leonardo Bonucci — as Juventus opened up a six-point lead over Napoli.
Ronaldo will miss only Juventus' home game against Young Boys on October 2.
It was Ronaldo's third goal in two Italian league games after the Portugal star took a while to get off the mark for his new club following his move from Real Madrid.
Ronaldo tangled with Valencia's Jeison Murillo, appearing to tug at the defender's hair, in the first half of Juventus' 2-0 win on Wednesday.
It was Ronaldo's first red card in 154 Champions League games, and the decision means he could miss a return to Old Trafford when Juventus plays Manchester United.
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