A 19-year-old man was found with a stab wound on the corner of Kitchener and Goulburn Street in Broadmeadows about 9.35pm.
He was taken to hospital with serious injuries.
Police had earlier been called to a brawl nearby and are investigating if the two incidents are linked.
It is alleged a group of men armed with machetes were fighting on Cuthbert and Joffre streets about 9.30am.
The group left the scene before police arrived.
Anyone who witnessed either incident is urged to contact police or Crime Stoppers on 1800 333 000.