Reece Sleeth, 20, faced the Bendigo Magistrates Court yesterday, where he pleaded guilty to the "cowardly" assault of a security guard outside the HuHa nightclub.

The court heard he had been using ice in the lead-up to the "king hit" and was drunk at the time.

Leading Senior Constable Denis Farrell said the attack happened during one of HuHa's "day parties" on July 14.

He said Sleeth had consumed a large amount of alcohol from 1pm and by 4.30pm had been told to leave the venue.

CCTV footage taken from outside Hu Ha, and shown to the court, shows Sleeth waited outside the venue for 10 minutes before approaching a security guard while his back was turned and "king hitting" him.

"The victim fell to the ground and was unconscious for two to three minutes," Leading Senior Constable Farrell said.

"The victim sustained redness, swelling and a mild concussion and was taken to hospital for treatment."

Leading Senior Constable Farrell said the assault had been "totally unprovoked" and was one of the worst police had seen.

The court heard Sleeth had a history of drug use including cannabis, amphetamines and ice but had stopped taking them since he was charged over the incident.

Sleeth's lawyer asked that his client's ongoing rehabilitation be given priority in sentencing, and requested that youth detention be considered.

But Magistrate Richard Wright said time in an adult prison was justified.

"This was a cowardly assault on a bloke who was just trying to do his job," Mr Wright said.

"There must be concerns about licensed premises running these sorts of events on a Saturday afternoon.

"I don't think youth detention sends a clear enough message that this needs serious condemnation from the court."

Mr Wright sentenced Sleeth to 15 months in prison with a non-parole period of nine months.

Sleeth immediately appealed the sentence and was released on bail.

Part of his bail conditions stipulate that he not attend licensed premises.

Sleeth was supported in court by his parents.

His father swore at police as he left the courtroom.