Mr Rogers on Tuesday told the court he saw his friend and Mr Pritzwald-Stegmann exchange words near the lifts, and that the surgeon put his bag on the floor, moved to "shape up" to the younger man and made physical contact.

"He was a tall fella, the doctor, and he chest bumped Joe [Esmaili], trying to intimidate," Mr Rogers said.

He said he did not see a punch thrown because the surgeon's body obscured his view. He said he saw the surgeon falling, but did not see his head hit the floor.

CCTV footage shown to court does not show Mr Pritzwald-Stegmann make any contact with Mr Esmaili, and does not show the surgeon's head hitting the floor.

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Mr Rogers said that after the incident, Mr Esmaili was angry with himself, called himself a "f---head" and an "idiot", but said the surgeon had kept "pushing" him.

The friend said he saw Mr Esmaili holding a six-pack of beer before they arrived at the hospital that day, but did not see the accused man drink anything.

Mr Esmaili kept his head down in the dock for much of Mr Rogers' evidence.

Prosecutors argue Mr Pritzwald-Stegmann suffered fatal skull fractures when his head hit the floor, and that Mr Esmaili's punch caused the surgeon to fall.

But the court heard treating staff at Box Hill Hospital detected only a singular skull fracture, whereas staff at The Alfred hospital later detected bilateral fractures.

Defence counsel John Desmond used the discrepancy to question doctors on whether the surgeon injured himself while agitated and moving on a bed, after the punch.

Erin Woodward, an emergency physician at Box Hill Hospital, said he and colleagues were "well versed" at ensuring agitated patients did not further injure themselves during treatment.

He said Mr Pritzwald-Stegmann-Stegmann was at one point restrained during treatment.

"I would be very surprised if he had hurt himself (during treatment)," he said.

Dr Woodward said the second skull fracture might not have been detected at Box Hill because of the different interpretations radiologists made of CT scan results, the way Mr Pritzwald-Stegmann
was positioned during the scan and whether he moved.

"Any movement by the patient during the scan will decrease the accuracy," he said.

Mr Desmond said if he did this week argue for charges to be withdrawn, he would submit that Mr Pritzwald-Stegmann died because life support was withdrawn.

Forensic pathologist Linda Iles said the surgeon would have died had he received no medical treatment the night he was injured.

The hearing continues.