I remember the first time I watched the fight all those years ago, thinking "come on, summon chief toad to drag his ass back." Lols. I keep running scenarios in my head and the only thing I can come up with is Sasuke escaping the whole fight with a substitution. I doubt a genjutsu would have worked considering Sasuke would have been new to it if he even had it. Plus, Gamabunta would have had Naruto to wake him up, and he's a huge, very experienced warrior in jutsus.