Ada Dinora Lachuga slowly climbed the stairs from the basement of her sister's Brentwood home Saturday, wincing as she eased herself onto the couch.

Lachuga, 52, was left with a broken rib, badly bruised knees and excruciating head pain after she was assaulted Friday as she walked home from the supermarket about 3 p.m., she said.

Suffolk police said they are investigating the incident in which witnesses said four men attacked the woman on MacArthur Avenue in Brentwood, punching her in the head and kicking her before fleeing.

The assailants took nothing but left her motionless on the ground, she said.

Her family believes Lachuga was a victim of the "knockout game," a growing trend in which unsuspecting victims are punched in the head in an attempt to render them unconscious.

"She believes that that was what happened to her because they didn't steal anything. She got punched, and that was it," said Lachuga's sister, Alba Juarez.

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Police have not linked the attack to the trend.

"She felt a really big hit on the head and then she doesn't know what happened," Juarez said Saturday, translating from Spanish for Lachuga, who sat in the living room, holding her side. "She didn't see anybody, she just felt a punch."

Witnesses called police and Lachuga was taken to Southside Hospital in Bay Shore and released after being treated, but she returned later because of vomiting episodes. She was given morphine for the pain, but she worries that she won't be able to return to her job as a landscaper until her rib heals.

For now, Lachuga said she's afraid to leave her home.

"It was very scary, when I got there and I saw the police there and my sister on the floor," Juarez said. "To know that it's happening here -- right here -- it's not just happening in the city . . . it's a scary thing."

No arrests have been made. Third Precinct crime control officers are investigating, police said.

Last week, a Rockville Centre man told News 12 Long Island he believed he was a victim of the "knockout game" after he was sucker-punched in the face about 2:30 a.m. on Manhattan's Lower East Side last Sunday. The 23-year-old told a reporter that he later woke up in an ambulance with his jaw wired shut.