Board Thread:Versus Debates/@comment-26998824-20151011185829/@comment-26537507-20151026100320

Sasuke held his own against Ay only through Susanoo and Blaze Release. Shisui would be a lot faster than Sasuke, but I would say that reaction speed is more important in this fight. Shisui's Susanoo has only been in a game so until it appears in other media it isn't considered canon.

So if Shisui's reactions are fast enough to avoid Ay's initial strike, then he can put Ay in a genjutsu and end the fight in a few seconds. If not, the power of Ay's attack would probably end it there.