Police have released vision of a man they want to talk to about a vicious one-punch attack in South Brisbane.
The 48-year-old victim was punched in the head after a brief verbal altercation with another man on Melbourne Street about 10.15am Saturday, police believe.
The pair exchanged words in passing before the brutal assault took place, with the victim getting knocked unconscious and falling to the footpath, police said.
Detectives on Sunday released vision of the man they think "may able to assist with their investigation" of the assault.
The alleged attacker is described as around 170cm with short dark hair and was wearing black shorts with a red shirt tucked into them, and white running shoes.
The injured man remains in the Princess Alexandra Hospital in a critical condition.
Police are investigating if it was a random attack, according to NewsCorp Australia.