Dybala scored twice as Juve downed Barca 3-0 in their quarter-final, first leg, but a knock in Serie A action has his participation in the return fixture in doubt.
However, speaking after the 2-0 league victory at the Stadio Adriatico, in which Gonzalo Higuain scored twice, Allegri was hopeful Dybala would recover in time to travel to Camp Nou.
"Dybala took a blow, there is a distortion," the Juve coach told Mediaset Premium. "But, with four days to recuperate before Barcelona, you have to be optimistic."
"We have to get to 91 points - Roma can do 90," he said. "Now we have to think about Wednesday [against Barca].
"Compliments are nice, but it takes more balance in football. We must not get excited or depressed."
And despite the comfortable win over bottom-of-the-table Pescara, Allegri was disappointed that his side did not build on their half-time lead after the interval.
"Juve deserved to win," he said. "In the second half, we wasted some time - we had plenty of space in front of us and we were not good at exploiting it.
"When we had possession of the ball, we had to do better."