The assault allegedly occurred while patrons were lining up to catch organised buses home from the Music In The Vines festival in Macarthur, about 300 km from Melbourne.
The man airlifted was to a Melbourne hospital after the incident.
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Police arrested three Portland men, two aged 45 and a 48-year-old, who are currently assisting police with their enquiries.
Detectives are appealing for anyone who was in the vicinity of the altercation or with information to come forward.
