The victim, aged in his 70s, remains in critical condition in hospital following the incident on the Drumlish Road in Omagh, Co Tyrone.
He was driving with an elderly woman, also in her 70s, in a blue Fiat Panda car when it and a red Massey Ferguson tractor crashed at around 4.45pm on Saturday.
The woman was treated for injuries, which were not believed to be life-threatening.
Police have appealed for witnesses to come forward.
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