A woman angling for more room on the No. 4 train maced a man when the two got into an argument Tuesday, police said.

The woman boarded the southbound No. 4 train just before 11 a.m., sat down, and tried to gain more room. But when she started pushing the 37-year-old man next to her, the fight got physical.

As soon as the train pulled into the 86th Street station on the Upper East Side, the woman pulled out her Mace and sprayed the man. The suspect, about 18 to 20 years old, then ran.

The man was taken to Weill Cornell Medical Center in stable condition. Another 47-year-old woman was affected but refused medical attention.