The Belgian missed the last few games due to injury but United have been on a great run of form in his absence.
In the aftermath of the game, Ronaldo again drew more derision from some Old Trafford faithful when he blatantly said Jose Mourinho's side didn't deserve the win.
But substitute Juan Mata's free-kick on 86 minutes sparked a stunning revival that breathed new life into the visitors' Champions League campaign.
"No team wins in Turin in the last nine years, how strong Juventus are", Guardiola said of United's eye-catching result.
"But we learned from out mistakes and we are still top of the group, so we are good".
"So if we win we are not only winning three points but taking three points from them as well".
Against an unbeaten Old Lady side who had only dropped points to Genoa at home this season, United hassled, harried, and looked as if they had a coherent game plan. "The top teams, you can not imagine and think about it, play amazingly for 90 minutes and they don't have chances". "If this answer is positive and we have, of course, one more session tomorrow, he's ready".
"We dominated the game for 90 minutes, had so many chances, could've killed it off three or four times, but we relaxed and were punished."
"The sensation when they have the ball with players in front, wow, they have incredible talent in front and the middle".
United's ability to snatch late goals under former manager Alex Ferguson was one their most potent weapons, an ability they have not managed to display with any sort of regularity since the Scot retired.
"Bring our game and control as much as possible, be clinical - that's the game we will try to do".