Luigi Spina, who had just finished work at a nearby Italian restaurant, went to assist a woman being attacked by a man on Yarra Promenade just before midnight. Victoria Police spokeswoman Creina O’Grady said when the 24-year-old tried to intervene, the man stabbed him on the left side of his abdomen.

Detective Senior Constable Jon Amore said people should phone police immediately rather than step in to help when witnessing an assault.

“It’s a heroic act saving a female in distress; he obviously was trying to do the right thing but as a result it hasn’t turned out too good for him — he’s received a stab wound,” Sen-Constable Amore said.

The attacker ran off along Yarra Promenade, while the victim approached a nearby parking attendant for help.

Mr Spina was in a stable condition in The Alfred hospital yesterday.

Police believe the offender and the woman did not know each other and the offender had tried to instigate fights with two others before the stabbing.

The offender is described as a white male about 20, 180cm tall with a stocky build. He was wearing a black-and-white cap and a grey, long-sleeved shirt with a large blue, white and red Tommy Hilfiger motif.

He was also wearing dark blue shorts and white runners, and carrying a black satchel.

Witnesses and other victims are urged to contact police.