We fight. I hit throws at me trying to kill You. You throw punches back at me trying to only counter my blows and match them. And then we both end up getting injured.. While the fact is if you had a killing intent.. and wanted to end me.. you could've done it long time ago.. But now you are f*cked up like me.. because you held back.
Since when did holding back = not running out of juice?

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Naruto didn't want to kill sasuke even once.. He never tried... he was only there to "carry" "endure" aka counter sasuke's attacks.. which required chakra.... And then you have the fact that he had to counter the chakra of 9-tailed beasts together...
BEcause hes out of chakra =/= he didn't hold back.