Police have arrested a man following an incident in Alfredton on Thursday afternoon.
Police said a 68-year-old man was found with life-threatening injuries after being bashed outside a Sturt Street motel.
Ambulance Victoria spokesman John Mullen said paramedics received the call at 5.15pm.
They arrived to find the South Australian man at the address.
Paramedics reported the victim had a large amount of bruising all over his body and was also suffering some back soreness.
He was taken to the Ballarat Health Services Base Hospital in a serious condition. He was then transferred to the Royal Melbourne Hospital where he remains in an induced coma.
Detectives from Ballarat Crime Investigation Unit are investigating the circumstances surrounding the incident and anyone with any information is urged to contact Crime Stoppers on 1800 333 000.
South Australian detectives yesterday arrested a 35-year-old South Australian man in relation to the incident.
Victorian detectives will travel to South Australia on Monday to apply for his extradition.