We dare suggest that that's what happened in Obara's second Japanese title defence when he took on Tetsuya Hasunuma and went into the 9th round for the first time in his career.
Obara is, and always will be, a power puncher first and foremost but against Hasunuma he seemed to be happy to become a boxer as opposed to a fighter, he was happy to work off his jab, use his movement and keep at distance as much as possible. He did throw some heavy artillery but somewhat less than he had in some previous fights until he felt he had proven his stamina to himself and went for the kill with some bombs in round 9.
This fight proved not only could Obara go the rounds but also that he really could box. He had been promising but had never displayed this level of boxing before and that, more than the rounds, was impressive.
(A big thanks to 45412380 for originally uploading this fight)