A motorcycle rider sustained critical head injuries after crashing into a car in Doonside on Saturday afternoon.
The man, 18, was riding down Hill End Road, Doonside when he ran into a car at speed about 4.20pm.
CareFlight's rapid response rescue helicopter carried critical care paramedics to the scene, while NSW Ambulance paramedics also arrived to treated the man.
He was sedated and intubated before being driven to Westmead Hospital in a critical condition.
Western Sydney Local Health District confirmed the driver remained in a serious but stable condition on Monday afternoon.