Well, kyuubi naruto was fast, but not in his combos, he was just a fast mover, his combos didnt even require the show to slow down , while neji vs. kidoumaru the world slowed to a crawl against the spiders, its like rock lee said, its ok if your eyes can keep up, but the question is can your body?, the speed of 128 strikes was already amazing, much faster then any combo any char in naruto has ever shown, so even though sasuke might see it coming, he wouldnt be able to react in time.

And like Strider said, neji would only need 1 touch on sasuke's body and it would be over, so even if it means the chidori would hit him afterwards, sasuke would die too, for me either neji wins, or its a draw