Here's one theory: The Naruto that used the kyubi power against neji was a clone. The real naruto, plus another clone was hiding in the shrubs or sumthing. After the last move, he clone that was fighting neji poofed away (like they do), then Naruto and the clone jumped into the cloud of dust. The real Naruto dug the hole, and the clone played dead.
I know it's most likely not the case, seeing as when neji used that divinity thing the clone shuld has disappeared, but it just a theory.