A sick sex fiend tried to rape a woman in a Brooklyn apartment building where she was visiting family Sunday morning, police said.

Cops said the creep trailed the 32-year-old victim into the building near Ralph Avenue and Bainbridge Street in Bedford-Stuyvesant at 8 a.m. and forced himself onto the woman in the vestibule.

The brave victim fought off her attacker, but lost her cell phone in the struggle with the perv, authorities said.

The suspect, who was caught on surveillance video near the building, stands 5-foot-11 and weighs 195 pounds.

He was last seen wearing a Yankees cap, a dark blue t-shirt, khaki pants, and black shoes.