Police have arrested a man in relation to what they're describing as a vicious, premeditated and unprovoked attack in Nelson.
They say a 56-year-old man was assaulted outside a hotel shortly before 1.30am on Saturday.
They say his attacker used a wooden bat and continued to hit him after he was knocked unconscious.
The victim was treated for a severe cut to his head and a suspected broken arm, and released from hospital.
Detective Sergeant Mark Kaveney says a witness tackled the alleged offender and tried to wrestle the bat from him.
He says a 34-year-old man located on Saturday with the assistance of the public has been charged with wounding with intent to cause grievous bodily harm and injuring with intent to injure.