Juventus were cruising to a comfortable win against the league newcomers in Turin after goals from Sami Khedira, Mandzukic and Hernanes wrapped up a fourth consecutive league win to move them seven points ahead of Roma before the remaining weekend fixtures.
But coach Massimiliano Allegri gave fans an indication of a likely future star of the club when he sent Kean on for a long-awaited debut having stunned observers with several impressive performances for the club's under-19 side.
Kean, who turned 16 on February 28, had little time to get into his stride but showed some fancy footwork on his way to winning a corner that, on the stroke of full-time, was not given.
It was a brief yet albeit promising cameo that will give fans around the world of seeing Kean, of Ivorian heritage but who has played at all levels for Italy, become the first player born after 2000 to play in the Champions League from next year.
He was not included in the club's 21-man squad list for the competition on September 1.
But Kean has already being watched by rival clubs in Europe, and Juventus CEO Beppe Marotta said he hopes Kean's agent doesn't have ideas.
"Playing at Juventus should be a point of pride for him. He's in the best possible place," Marotta told Mediaset Premium.
"If it comes down to money, that's a different story. His agent should reason with him, it shouldn't just come down to money."
Allegri said: "He has the chance to play alongside top players here. He has soak up what it's like to be part of a great squad.
"His attitude will make the difference."
Juventus are away to Sevilla on Tuesday in a bid to secure their last 16 ticket in the competition and Allegri added: "It's an important game for us because we have to win one of our last two games to go through."
Earlier, a second-half brace from Lorenzo Insigne boosted Napoli's hopes of maintaining Champions League football in a 2-1 win at Udinese that pushed the southerners up to fourth at six points behind Juve.
It helped Napoli return among the top five after a six-game streak that featured only two wins, and three defeats.
Amid a seven-month goal drought, Insigne looked the last player to get his name on the scoresheet.
Playing in spite of a bout of flu amid injuries to striker Arkaduisz Milik and Manolo Gabbiadini, Insigne turned on the style in 10, second-half minutes to claim his maiden league goals of the season and his first since April.
"It was obviously he was going for at least a brace," said coach Maurizio Sarri.
"I could see it in the way he reacted after hitting his first goal. He was reborn and about to become very dangerous every time he touched the ball."
When Insigne found himself in space on the edge of the box two minutes after hte restart, he promptly fired Jose Callejon's pinpoint delivery into the roof of the net.
Orestis Karnezis then produced a fine, fingertipped save to push Insigne's drive over the bar and, when left unmarked 12 yards from goal, the Italy forward ballooned over.
Persistence paid off, though and Insigne's double was complete on 57 minutes, beating Karnezis one-on-one after outfoxing Widmer.
Stipe Perica rose at a corner to send a powerful header past Reina only two minutes later but Napoli saw further chances by Insigne, Mertens and Giaccherini keep the pressure applied until the final whistle.
Napoli returned to the Champions League group stages this campaign and host Dinamo Kiev at the San Paolo stadium on Wednesday looking to boost their last 16 qualifying hopes.