A naked man attempted to rape a 23-year-old Brooklyn woman as she walked home from work Monday night, grabbing her by the neck and throwing her to the ground, but the woman escaped, police sources said.

The attacker, believed to be mentally unstable and between 25 and 30 years old, was already naked when he approached her at 11:15 p.m. in the vicinity of East 55th Street and Avenue J in Flatlands, sources said.

He told her to keep quiet and that he wasn’t going to rape her, even as he tackled her and forcibly touched her, sources said.

She fled and contacted police. The suspect remains at large. The NYPD’s Special Victims Unit is investigating.