Police said a man was driving was travelling north along the Midland Highway near Yenden Number Two Road when  the car he was driving swerved onto the wrong side of the road and collided with an oncoming car just after 10am. 

A witness said he had had a near miss before with the car before it hit the the one the woman was driving. 

"He's come onto the wrong side of the road, hasn't braked or anything," he said.

"I've swerved and he's hit the car behind me."

Senior Sergeant Peter McCormack said the man died at the scene. 

Sergeant McCormack said they would look into all aspects of the crash.

"At this stage, we're still exploring avenues of causes," he said. 

"We've got one 19-year-old male deceased...and a (39-year-old) female that's been trapped in the car," he said. 

The woman's condition was later revised down to serious but stable. 

She was diagnosed with a broken leg and arrived at The Alfred hospital just after 1pm, Ambulance Victoria spokesman John Mullen said. 

Both drivers were the only occupants of their vehicles. 

Anyone who witnessed the collision is urged to contact Crime Stoppers on 1800 333 000.