Police have arrested a man following an incident in Brunswick West overnight, Victoria Police say.
Police were initially called to reports of a male acting suspiciously on Heller Street, near Grantham Street, about 1.20am.
The man, who had a stolen motorbike with him at the time, was seen by police allegedly tampering with another motorcycle.
He fled when approached by police, but was arrested nearby a short time later following a brief foot chase.
During the arrest, the man, who was wearing a helmet, allegedly head-butted a male Senior Constable.
The officer was taken to hospital with minor injuries.
The male in custody, a 38-year-old from Thornbury, was taken to hospital for assessment of chest pains.
The investigation is ongoing.