Police are investigating a disturbing road rage incident in Brisbane’s south-west that has left a man in a serious condition in hospital.

A 34-year-old man was the passenger in a Volkswagen Golf travelling on Douglas Street at Oxley at around 3pm on Sunday.

Police say a truck driver had allegedly been driving dangerously while overtaking the car.

Both drivers soon pulled over.

The truck driver then attacked the passenger of the car with a large stick, before driving off.

He was taken to hospital in a serious condition with a significant head injury, a fracture to his hand along with lacerations and bruising.

Anyone who witnessed the incident or who has CCTV or dashcam footage is urged to contact police, as investigations continue.

Press PLAY below to hear the latest from Nine News reporter Annie Puller