A good Samaritan was bitten and choked on the D train at Columbus Circle Saturday, in the latest off-the-rails subway attack.
The suspect was harassing a passenger on the uptown train around 5 p.m. when another straphanger intervened, police said.
The 44-year-old suspect turned his ire on the do-gooder, and attacked him with his mouth and hands, according to the NYPD.
Police arrested the unnamed attacker, and the victim went to the hospital for treatment of his injuries, police said.
The attack comes a day after four people were slashed and one was punched at three Manhattan stations in a 12-minute span, by a group of suspects on a subway crime spree.
The latest brazen attacks underground have MTA officials and many candidates for mayor calling on City Hall to beef up police presence in the subway.