A killer is being hunted over a stabbing death near a Melbourne service station on Tuesday.

A 39-year-old man collapsed and died outside a BP on Potter St at Dandenong about 4.50am.

It is understood he had run from a next-door residence, where police believe he was stabbed.

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Officers patrolling on the Princes Hwy saw the victim as he collapsed on the roadside and rushed over to find he had been stabbed.

They provided medical assistance until paramedics arrived, but the man was unable to be saved.

He is yet to be formally identified.

Detectives are now speaking with the first responders to gain insight into anything the victim might have said before he died, as they launch a homicide investigation.

A phone was also found nearby, but it is not yet clear if it is related to the investigation, Victoria Police Homicide Squad Detective Inspector Dean Thomas said.

Thomas said police believe the attack was targeted.

But who the killer is, and their relationship to the victim, remains unknown, as does the victim’s connection to the property where the stabbing is believed to have occurred.

Anyone who was on Potter St, or the nearby Princes Hwy, at Dandenong, from about 4am to 5am on Tuesday is urged to contact Crime Stoppers.