A man has been stabbed during an apparent road rage incident in Melbourne's west.

Police say two men were driving along Neale Road, Cairnlea on Tuesday night, when they both stopped their cars in the right turning lane.

The two men got out of their vehicles and started fighting.

A man aged in his 50s was stabbed, and taken to Royal Melbourne Hospital in a serious condition.

The offender fled the scene in his vehicle and is yet to be found.