It sounded like bad english to me, I took it to mean he wasnt tiring and he had alot left for the last part of the fight.
Zaveck would have got stopped either way. He likely was behind on the cards though the fight was close. Berto was landing cleaner shots and making the fight.
dude before the headbutt Zaveck had his face as at the start of the fight...he started to take fight on his own hands and made 40% of realisation of the punches (while berto only 25%) and also Zaveck lended more punches then Berto...so if something unexpected would happen i think your boy would, who was already running out of gas, would be even KO in round 10-11!