Police are investigating separate incidents that occurred in the early hours of Sunday 1 January.
At about 12:05am, a 16-year-old male was thrown from his motorcycle when he collided with another motorcycle rider in Ferndale Road, Upper Ferntree Gully.
The child was not believed to be wearing a helmet.
He was conveyed to hospital with serious but non-life-threatening injuries.
The other rider received minor injuries.
Knox HWP members are investigating the circumstances of the collision.
Anyone with information is requested to contact Senior Constable PHILLIPS on 9881 7900/9881 7000 or submit a confidential report via CrimeStoppers.
At about 1:30am, a 28-year-old male driver lost control of his vehicle in Black Springs Road, Wonga Park and collided with a tree.
His vehicle overturned and he was trapped inside for some time until he was able to be freed by emergency services.
He was later conveyed to hospital via air ambulance with serious but non-life-threatening injuries.
Police are investigating if speed, drugs or alcohol contributed to the collision.
Please contact Senior Constable JENNER at Yarra Ranges HWP on 9739 2402 or make a report via Crimestoppers if you have any information, CCTV or dash cam.
In a Facebook post, Yarra Ranges Eyewatch said “it is disappointing that despite our best efforts to warn people about the consequences of risk-taking behaviour, particularly at this time of year, that we are still attending a number of avoidable motor vehicle collisions”.
“Don’t drink or take drugs and drive, and remember that YOUR poor decision may have long-term consequences for many others,” the post read.