An argument between two men on a Mackenzie Country dairy farm turned violent on Monday, when one man was allegedly attacked with a knife.
Police were called to the incident at a property between Omarama and Twizel on State Highway 8 about 10am.
Detective Constable Anton Perham, of Oamaru, said police were still piecing together exactly what happened before the attack, which he described as "a little bit odd".
Early indications were an argument between two men, who both worked on the dairy farm, became heated after one of them "flipped out" and produced a knife, Det Const Perham said.
The man attacked suffered a small cut to a hand and another to his chest after his attacker lunged at him with the weapon.