Patrick Pritzwald-Stegmann (41) suffered head injuries last May when he fell at Box Hill Hospital after allegedly being struck to the head by 24-year-old Joseph Esmaili.
The surgeon's life support was turned off weeks later. Esmaili is on trial in the Supreme Court, having pleaded not guilty to manslaughter.
Despite recanting his early claim he saw the doctor get punched and fall, Esmaili's friend Corey Rogers told the court he witnessed Esmaili's response.
"Oh f***. He made me do it," he said Esmaili had yelled out, before jogging outside the hospital and running with his group toward Box Hill.
Hospital receptionist Megan Brodersen had called security over a radio from her reception desk to come quickly to break up an argument between the two men when she heard a bang, she told jurors on Thursday.
She looked up and, through a reflection in a window, saw Dr Pritzwald-Stegmann, a surgeon at the hospital, on the ground.
Ms Brodersen recalled rushing to his side, seeing him unconscious, choking and not breathing.
She called for help and moved him to the recovery position.
"He was very stiff, kind of convulsing. I put him in the recovery position an that's when the blood came out of his nose and mouth" she said.
"It felt like forever but (help) came very quickly."
In the lead up, Ms Brodersen said she heard Dr Pritzwald-Stegmann tell Esmaili "you can't talk to me like that" and repeatedly asking, "did you just spit on me".
Administration worker Lucy Jackson said she saw the punch reflected through a window, but under cross-examination by Esmaili's barrister John Desmond, admitted she didn't see Esmaili's fist connect.
It's alleged the argument began after Dr Pritzwald-Stegmann asked a group outside the hospital to stop smoking in a non-smoking area.
Leigh Clayton, one of the smokers, told the court earlier on Thursday the doctor seemed angry and frustrated they failed to move on as he had asked and he "stormed back inside" to get security.
"He was pissed," she said.
Witness Lucas Rogers said on Wednesday of Esmaili, recounting a conversation after the alleged attack that "when someone pushes him like that it was hard to control his anger."
Mr Rogers had met Esmaili a few times as the defendant was friends with his nephew, he told the court.
From up to 30m away, the labourer had witnessed an argument escalate after Dr Pritzwald-Stegmann asked someone in a group to stop smoking in a non-smoking area at Box Hill Hospital in May last year.
"It looked like they were arguing, the doctor appeared to escalate the aggression," Mr Rogers said.
"I think he bumped chests with him. I saw that."
The witness said Esmaili later told him he "just wished the bloke would have left him alone".
Another witness who was at the hospital at the time said she saw the lead-up and aftermath of the punch.
In her statement to police, Holly Poulse said it was "obvious" the pair were in a heated argument.
"I saw the man fall to the ground like a log and hit the hospital tiles," she said.
Dr Pritzwald-Stegmann suffered head injuries when he fell and spent about a month unconscious in hospital before life support was switched off.
Esmaili's trial is due to continues.