A MAN who came forward in relation to the footpath fight which left Jason Toby fighting for his life in hospital has been released without charge.

Queensland Police said the man voluntarily attended Petrie Police Station about 4pm Sunday in relation to the incident.

He was released without charge about 7.30am Monday, with investigations into the assault continuing.

Mr Toby remains in the Royal Brisbane Hospital in a critical condition.

The 38-year-old was out with his wife Britt Potter in Brisbane's CBD when police said the couple began arguing on the footpath outsider the Aurora Tower early Sunday morning.

VIOLENT NIGHT: JASON TOBY FIGHTS FOR LIFE AFTER FOOTPATH FIGHT

media_camera Man released after violent footpath fight

The couple were arguing on the footpath of Queen Street near the intersection with Wharf Street around 4am Sunday when an unidentified man stepped in, seriously injuring the 38-year-old.

Earlier, Brisbane region detective inspector Ian Park said Toby was in a critical condition with serious injuries after being resuscitated at the scene.

Insp Park said alcohol may have been a factor.

"I guess it's a fair assumption that at 4 o'clock there is going to be alcohol involved, so we would appeal to people to just be careful with alcohol and look after themselves and each other and not to drink to excessive levels, which is always a deadly cocktail."

There were reports that people performed CPR on Mr Toby before paramedics arrived.

Alessandro Vosolo, who is staying on the 44th floor of the Aurora Building, said the fight sounded violent and lasted less than four minutes.

"Fighting, screaming, arguing like guys getting thrown around, that sort of thing," he said.

One witness said he was on the 20th floor of the hotel and heard the fight.

"A dude got beat up ... We heard it but then police rocked up."

It was a violent night on the streets of Brisbane.

Detective inspector Ian Park said police were also investigating the assault of a man who got into a fight with a hotel staff member at the Orient about 4.30am.

A 37-year-old man fell down the stairs and suffered serious head injuries when his head hit the concrete pavement.

"I believe the may have been a disagreement between this person and a staff member but as to what actually took place is subject to investigation," Insp Park said.

The man was taken to the Princess Alexandra Hospital where he is in a serious condition.

In a third incident, a man was allegedly glassed in the face at the Family Nightclub on McLachlan St in the Fortitude Valley about 3am Sunday.

Police said a 19-year-old was struck in the face with a glass, receiving cuts to his cheek area. Police said the man did not have life-threatening injuries.

A spokesman said security staff and patrons stopped the alleged attacker and held him until police arrived.

A 20-year-old Calamvale man has been charged with assault occasioning bodily harm. He is due to appear in the Brisbane Magistrates Court on Monday morning.

Editor's note: An earlier version of this story did not clearly identify Mr Toby as Ms Potter's husband. We have altered this information at her request.