I saw the matrix-spoilers

[Rndm_Perfection]

Originally Posted by Blackmane

That would explain why it had to be Neo that would stop him, but it still doesn't quite make sense why he had to fight. He could have just given in and then killed him. Perhaps he had to show persistance in order to maintain some control of himself in order to delete Smith, or else he would have been permanently controled and Smith would have won.

I think Neo fought because he wasn't quite sure he had the ability to mess with Smith from the inside. Then again... I wonder how he thought it was possible to beat all of the Smiths one-by-one (Even if the first, the Oracle, was the strongest) in hand-to-hand combat.