Napoli medical chiefs fear a serious knee injury for Diego Demme.

The Germany international was brought down by a strong tackle from a Pro Vercelli player in a friendly yesterday.

After several minutes of treatment, he was carried off by two members of the medical staff.

A statement confirmed an injury to the right knee and more tests will be performed tomorrow, suggesting possible ligament damage.

Sky Italia is reporting that medics fear it is anterior cruciate ligament damage.