He didn't win and he wasn't alone.The strongest character Sasuke has fought alone? Bijuu Mode Bee. It was basically Chidori and Amaterasu versus BM Bee. Sasuke came out victorious. Bee states himself that, "well, that Sharingan dude's probably the toughest fellow I've ever fought," and that he thought of Kawarimi on the fly - VIZ.
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He alone managed to push him to BM after surviving lariat so i'll give him that.