The crash happened on the Henty Highway about 3pm on Sunday.

Ambulance Victoria spokesman John Mullen said the man was in his 40s.

"He was in a serious but stable condition with chest, head and back injuries," he said.

Northern Grampians Highway Patrol also attended a single-car crash at Stuart Mill just before 1pm.

Paramedics assessed and treated a woman, 19, at the scene after she crashed her car into a tree on the Sunraysia Highway.