Woman stabs sex attacker in Melbourne park

A man who sexually assaulted a woman in a Melbourne park has been left with a stab wound after she managed to turn his own knife on him and escape.

The 32-year-old victim had been walking a friend's dog at Thornbury on Saturday night when she crossed the road into Mayer Park to avoid a man acting suspiciously.

But the man followed her, claiming he needed help finding something before pulling out a knife, pushing the woman to the ground and sexually assaulting her.

She managed to grab the knife and stab him before running with the dog onto the road and flagging down a passing car.

"It's quite frightening. I think he was on a mission and he saw the woman coming and he pursued her," Detective Acting Inspector Janet Mitchell told reporters on Sunday.

"When he could see that she was trying to get away, he's tried to divert her attention, appealing to her good nature to assist him.

"It could have ended up much worse. I think the woman was very brave to act the way she did."

The woman was taken to hospital but has since been released.

The attacker fled and detectives are urging people to be on the lookout for a Caucasian man in his early 20s with a stab wound.

He has brown hair and was wearing loose pants and a hoodie. Police have released a computer-generated image of the man they're looking for.

The attack occurred about 10.30pm and police want anyone with dash cam footage or CCTV from Normanby Avenue or Leinster Grove to contact them.

It follows a string of high-profile assaults on woman in public places across Melbourne.

Courtney Herron, 25, was bashed and killed at Parkville's Royal Park in May. Henry Hammond is charged with her murder.

In January, 21-year-old Aiia Maasarwe was raped, murdered and set on fire near a Bundoora tram stop. Her attacker, 21-year-old Codey Herrmann, is awaiting sentence.

Budding comedian Eurydice Dixon, 22, was raped and murdered while walking home through Princes Park at Carlton North in June last year.

Jaymes Todd is appealing against his life sentence over the attack.