A 28-year-old man was stabbed on a Manhattan train Thursday — in another random attack on the transit system, police sources said. 

The victim was on a downtown F train at the Lexington Av/53 St. station around 1:30 p.m. when a stranger knifed him in the torso, according to the sources and police.

Medics treated him at the station, and his injuries were not life-threatening, the NYPD said.

His alleged stabber — wearing all black clothing with bleach stains — was collared by police on the F train platform at the Delancey St-Essex St. station a short time later, according to sources.

The unprovoked attack came a day after a 30-year-old woman was shoved into a departing F train at the Fifth Avenue/53rd Street station, leaving her clinging to life.

Suspect Sabir Jones, 39, was arrested Thursday in Newark, New Jersey, for allegedly randomly pushing the woman, causing her to hit her head on the train and then tumble down onto the tracks.