The game had got off to the kind of start that most had expected when Juventus took the lead through Sami Khedira early on, before Stepinski equalised for the home side just before half time.
Chievo came out in the second half with the confidence that they had earned from getting that equalising goal before the break and wouldn't let the Juventus defenders rest.
Former Sunderland winger Emmanuele Giaccherini looked to be aggressive as he drove in to the box and was brought down by Joao Cancelo.
The referee pointed to the spot, and the player who won the penalty cooly sent Szczesny the wrong way to give his team a surprising lead.