A divorcee and three others attacked her former husband and his new wife following an argument over a phone number at a block of flats in Cheras, Harian Metro reported.
The 1am attack on Monday happened when the divorcee, accompanied by two men and another woman, went to the flats where the couple stayed and asked the new bride for her husband's phone number.
The younger woman refused, saying she did not have her husband's permission to share the phone number with anybody.
This angered the divorcee, who swung a helmet and a chain lock at her victim's head, causing her to fall.
"When the victim fell, the woman's friends joined in," said a source, adding that the husband rushed to her side to fend off the attacks. He was also beaten up.
The attackers fled when neighbours, who heard the commotion, came to help.
The victims suffered head injuries and bruises all over their body and were rushed to a nearby clinic for treatment.
The battered couple then lodged a report at the Sungai Besi police station.
A police spokesman told the paper they were investigating the incident.
It is understood the divorcee had asked for the phone number to harass her ex-husband over an unsettled matter.