A teen boy was viciously stabbed in a Harlem fight yesterday, police said.

An unknown assailant slashed the 14-year-old in the left side of his head, ear, and neck about 8:25 p.m. on West 125th Street, near Broadway, cops said.

The teen was rushed to St. Luke’s Hospital, where he was listed in stable condition. He is not cooperating with detectives, police sources said.

No arrests have been made.