Mario Mandzukic and Benedikt Howedes have been left out of the Juventus squad for Friday's top-of-the-table Serie A clash with Napoli.

The duo picked up injuries during training on Thursday and will not be involved at the showdown at the San Paolo.

"Mario Mandzukic is unavailable after picking up an injury to the calf muscle in his left leg, while Benedikt Howedes has picked up an injury to the quadriceps muscles in his right thigh, both during the course of today's training session," Juve confirmed via their official website.

Striker Gonzalo Higuain is in the squad despite head coach Massimiliano Allegri's concerns about rushing him back too soon following hand surgery.

There were also doubts about Juan Cuadrado and Federico Bernardeschi but both have been included in the 21-man travelling squad.

Champions Juve head into the match four points behind Napoli, who are top of the table and yet to be beaten in the league this season.