A driver is on the run after he stabbed another man in a brutal road rage incident that involved two cars repeatedly ramming each other in broad daylight in Hallam on Wednesday afternoon.

Police said that a white Daewoo ute rammed a blue Mistubishi Pajero on Belgrave-Hallam Road in Hallam, near Narre Warren in Melbourne's south east, about 2.30pm on Wednesday.

The drivers stepped out of their cars and started physically fighting near the Monash off-ramp.

Once the fight had died down, the Mitsubishi driver began to leave the scene when the Daewoo rammed his car two more times.

The Mitsubishi driver then emerged from his car and stabbed the Daewoo driver, who was taken to hospital.