The incident happened at about 4:45 p.m. near Sixth Avenue and Canal Street at the SoHo-Tribeca border.
Police say the 44-year-old victim and a friend were walking down to the A/C/E platform at the Canal Street station when they accidentally bumped into the suspect, who was dressed in a trench coat.
After a physical dispute ensued, the suspect pulled out a small pen knife and slashed the victim on his temple and wrist.
After being slashed, the victim chased the suspect for blocks and threw a piece of plywood at him.
The NYPD describes the suspect as a black male, 20 to 25 years old, 6'.2", 170lbs., and was last seen wearing dark clothing, fleeing towards 6th Avenue.
Anyone with information in regards to this incident is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782).