Juventus broke the deadlock through Bernardeschi – making a rare start for the Serie A champions – when he unleashed a fierce volley on goal from outside the box, following some good work by Paulo Dybala and Douglas Costa.
Juve went on to win the contest 4-1, but manager Massimiliano Allegri was far from happy with what he saw from his players.
"If we play like this at San Siro against Milan, we will certainly lose," he told Mediaset Premium after the game.
"We still haven't worked out that it's nice to score good goals but that we've got to keep the intensity and concentration up."
Paulo Dybala followed Bernardeschi's opener with a corking free-kick, before Gonzalo Higuain and Juan Cuadrado rounded off the scoring to keep Juve three points behind leaders Napoli.
