The attack happened at her home in the 4500-block of South Lacrosse at around 1:30 a.m.
The victim used a metal curtain rod to try to fend off her attacker.
The woman, who lives alone, told ABC7 that for weeks there have been suspicious late-night knocks on her window.
It happened again Saturday morning, she said followed by repeated knocks on the door.
When she opened it, curtain rod in hand, the victim said the lone attacker forced his way inside and then punched her in the head before sexually assaulting her.
Neighbors expressed fear and shock over the incident.
"We never had no problems like this before," said David King. "Never have. And for this to happen here is something that's very unusual."
"She's the type of lady?she don't bother nobody but if she sees you, she will speak to you," said neighbor Roderick Little. "And by me hearing this, I'm wondering why somebody would want to do that to her."
A neighbor a few houses down who was walking his dog, said he called 911 after hearing commotion.
The victim said the attacker was still in her house when police arrived on the block and said the man fled through a side door when he saw the flashing lights.
Police have only a vague description of the attacker. They said he was wearing a white t-shirt underneath a beige sweater with black pants and a black baseball-type cap as well as a large beige and white watch on his right wrist.
The victim said she may have left bite marks on his arm and hand.
"Each and everybody in this community looks out for each other, we always have," King said. "And that's what we're doing now, just looking out for her."