The father of the teenager killed by an alleged one-punch attack has described his son as a “beautiful, brave young man”.

Cole Miller, 18, was knocked unconscious on Duncan Street in Fortitude Valley in Brisbane’s entertainment precinct about 3:35am on Sunday after a night out on the town.

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He died in hospital on Monday afternoon “as a result of massive brain injuries”.

Police said he was struck once in the back of the head and hit the pavement. He was rushed to hospital in a critical condition that night.

“It is with deep sadness that I announce that our 18-year-old son Cole has today passed away as a result of massive brain trauma,” his emotional father, Steve Miller, said on Monday afternoon.

“Our family and many close friends have been by his bed side since the incident,” Mr Miller said.

Cole Miller in a photo from his Facebook page.

“[Cole was] a beautiful brave young man with his whole life to be lived.

“I want to thank the support provided by Cole’s school friends and the water polo community and the many many many others that have sent messages of support and hope.”

Armstrong Renata and Daniel Maxwell, both 21, faced Brisbane Magistrates Court earlier on Monday charged with grievous bodily harm over the assault of the young water polo player.

The court heard Maxwell approached Mr Miller and his friend and asked them if they wanted to fight before Renata allegedly punched Mr Miller in the head.

Both were remanded in custody.

Queensland Police Detective Tom Armitt said the death was “absolutely tragic”.

“A young innocent man walking on his way to catching a cab, there are no words to describe it other than than tragic,” Mr Armitt said. “We’ll be reviewing our charges and they will be heard at the next court appearance.”

He confirmed that while there was a group involved in the incident, only the two men already before the courts would face charges.

“People just have to be reminded that they are responsible for their actions and any acts of violence will be investigated and will be prosecuted,” Mr Armitt said.

The accused men will have their cases mentioned again in February.

Mr Miller was a member of the Brisbane Barracudas Water Polo Club and was out with a teammate on the night he was attacked.

They were taking a break from their busy training schedule. He was due to travel to Adelaide to compete at the national championships on Thursday.

– with ABC and AAP