A subway rider was stabbed while trying to help a woman who was being harassed at a Bronx station overnight, police said – just hours after the National Guard was called in as part of desperate new crime-fighting measures for the city’s troubled transit system.

The latest underground attack was reported at 12:50 a.m. at the Pelham Parkway station on the 2 and 5 lines, according to cops.

A 53-year-old man was getting off a northbound train when he saw two men — one dressed in all red and the other in all blue — harassing a woman, the NYPD said.

The good Samaritan intervened to help the woman and was stabbed in the right hand with an unknown object, according to the police.

The victim was taken to Montefiore Medical Center, where he was listed in stable condition.

The suspects ran from the subway station and fled in a white vehicle, cops said.

The violence comes after Gov. Kathy Hochul suddenly announced a plan to deploy 1,000 National Guardsmen, state police and MTA cops to check commuters’ bags in the city’s crime-ridden subway system.