Emergency services were called to the Sporting Globe Bar and Grill Bendigo, in Central Victoria, about 9pm on Thursday, Victoria Police said.
The 41-year-old man was treated by paramedics at the scene before being taken to hospital in serious condition with suspected stab wounds.
Police believe he had been sleeping rough and was set upon by up to six offenders following an altercation in nearby Bath Lane.
It is alleged the offenders, believed to be teenagers, fled the scene and left the injured man to search for help.
An Ambulance Victoria spokesperson told AAP the man was transported by road to Bendigo Hospital in stable condition with upper body injuries.
The venue issued a statement on Friday morning, saying "We are deeply concerned by an incident that occurred nearby late yesterday evening, in which an injured person made their way to The Sporting Globe Bendigo at approximately 9pm and collapsed in our sports bar.
"Our staff acted immediately, contacting emergency services and initiating first aid."
Owner Leigh Stevens praised the efforts of his staff in a note shared alongside the statement
"The only thing I'd like to add is that I'm extremely proud of how my staff and patrons acted during this incident," he told AAP.
"They provided first aid until emergency responders arrived and should be commended."
The venue said the incident was the first of its kind.
"An incident of this nature is entirely unprecedented in our venue and the surrounding area, which has always been a safe and welcoming environment," it said.
Police are appealing for anyone with information to come forward, after a preliminary search was unable to find the alleged offenders.
Detectives are expected to revisit the area on Friday morning.
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