Allegri gave Douglas Costa his second start this season up front alongside Dybala and Ronaldo, who was presented with a special jersey before the match after last week becoming the first player to break the 400-goal mark in Europe's top five leagues.
After struggling in a 4-4-2 formation against Empoli, Juventus could switch to a 4-3-3 this weekend with Blaise Matuidi being deployed in midfield alongside Rodrigo Bentancur and Miralem Pjanic.
Paulo Dybala scored after 44 seconds for Juventus but they were made to struggle in a 3-1 win over a courageous Cagliari team as they stayed six points clear in Serie A on Saturday. We can't afford to drop any points.
Centre-back Giorgio Chiellini and winger Federico Bernardeschi continued their recovery regimes after injury, and the pair should be available for selection against United.
Cagliari pushed forward with Artur Ionita setting up Leonardo Pavoletti but Wojciech Szczesny cleared, before Pedro broke through.
Pjanic declared that he wants to win the Champions League, the competition that has evaded Juve for the last 22 years.
Juventus are the only unbeaten team in Italy this season, having won nine of their ten games in the league thus far.
"As for Cristiano, he is a monster".
Then Cristiano Ronaldo provided the assist for Juan Cuadrado's goal hand Max Allegri's side all three points.
Therefore, he has been the only bright spark in a Juventus team, who have underperformed in recent weeks.
Speaking to Sky Sports (via Calciomercato), the Bianconeri boss said: "Even in Madrid he was a leader, he is an extraordinary player, even when he does not score goals he sets others up like he did for Cuadrado in decisive moments, goals or puts the ball right". "When I say quality I don't just say creative players - Chiellini and Bonucci, it is absolutely lovely to see". "We have to be capable of grinding out 1-0 wins too", Juventus coach.