Dybala scored the game’s only goal as Juve recorded a 1-0 victory at Old Trafford on Tuesday.
“I thought that he [Dybala] put in a great performance, I have to say,” Allegri told a news conference.
“So he didn’t play, came back and did ever so well I thought.”
Allegri explained his decision to substitute Dybala in the 78th minute, saying more energy was needed in his team.
“I thought it was a period of the game when we needed to have fresh legs. We needed to stretch the opposition, stretch the game out,” he said.