Man pleads guilty to one-punch assault (AAP)

A man who punched a fellow partygoer for no reason at a Sydney nightclub has pleaded guilty to the attack.

Sebastian Bell, 24, had come to Sydney to enjoy a night out with friends last November when he went to Candy's Apartment in Kings Cross in the early hours of the morning.

But while on the dance floor of the Sydney club, the university student was suddenly punched on the left side of his head by Christopher Speight.

The attack continued as Speight straddled him and attempted to land more blows on him before Mr Bell's friend intervened, court papers state.

Speight, 29, pleaded guilty to one count of recklessly causing grievous bodily harm at Downing Centre Local Court on Tuesday.

Facts tendered to court say Speight can be seen on CCTV footage at the nightclub standing by himself on the dance floor.

He is seen staring towards Mr Bell's direction before picking up a schooner glass and downing its contents.

Moments later he walks over to Mr Bell and throws a punch with his right hand, knocking the student to the floor.

When police questioned him over the attack in January, Speight told them it didn't sound like anything he would do, adding "I've never hit anybody in my life".

Upon seeing CCTV footage of the night, Speight said: "I don't remember but if I was there, I must have been drinking a lot.

"It looks like I just hit someone for no reason."

Speight said he had no idea how he came to the nightclub strip last November.

Although he didn't go out often, when he did he said would drink a lot and would sometimes experience black outs.

Mr Bell has had a metal plate inserted into the part of his jaw which was fractured by Speight, court papers say.

The 29-year-old will be sentenced at a later date.

http://au.news.yahoo.com/a/-/latest/24695235/man-pleads-guilty-to-one-punch-assault/