 Na only Tommy Burns  11  , Vitali Klitschko  11  , Wladimir Klitschko  18  , Larry Holmes  20  and Joe Louis  25  don manage to defend dia heavyweight crown more times straight without defeat .  O O B-PER I-PER O O O B-PER I-PER O O O B-PER I-PER O O O B-PER I-PER O O O B-PER I-PER O O O 