Board Thread:Theories and Speculation/@comment-31338621-20180506051005/@comment-35409024-20180511185554

The whole point of the fight between Sasuke and Itachi was not because he wanted to test Sasuke's strength, but to ware him down to remove Orochimaru from him, implant Amaterasu in Sasuke just in case he met Obito, and to satisfy Sasuke enough that he'd return to Konohagakure and live the remainder of his life inhibited by the fact that the man who slayed his entire clan for sport was still out there.