Cops are searching for a man they say slashed a subway rider who got into a fight with a woman on the train in Harlem Sunday, police say.

A man and a woman began arguing on the southbound 2 train in Harlem just after 3 a.m. Sunday, according to police.

When the train pulled into the 110th Street station, a man waiting on the station platform confronted the man involved in the argument, police said.

The two fought, and the suspect cut the victim with a knife over his left eye, police said.

The man and woman then ran out of the station.

Despite a spate of recent high-profile slashings and assaults on the subway, Mayor de Blasio and Police Commissioner Bill Bratton say the first month of 2016 has been the safest since NYPD began keeping records.

Bratton also said more officers were being added to subway patrols.

The suspect is described as about 6 feet 2 inches and 200 pounds. Anyone with information is asked to contact Crime Stoppers at 800-577-TIPS.