I remember when this fight happened, I watched it live, I was always a huge Wlad K fan. Immediately after the fight, Wlad claimed he had been poisoned or drugged. If I remember correctly, he also claimed that vaseline was smeared all over his body and that made him tired, or unable to breathe or something.
At first, I dismissed those claims as just "sour grapes" after losing a fight. But, if Ive learned anything watching boxing, it's that boxing is a shady sport and now I would say its certainly possible.
Before Wlad had that collapse, Wlad dominated the whole fight, even dropping Brewster, but he simply ran out of gas and was exhausted. Wlad was exhausted in that fight against Brewster. Brewster, to his credit is an extremely tough guy. Had Brewster ever fought someone like Lennox Lewis or Mike Tyson, I'd give him a real good chance at pulling an upset over either one of them. Brewster hits very hard, and this guy will keep coming the whole fight. He's not an easy fight for anyone in boxing history, and he would pull a lot of upsets against champs from the past.
Wlad and Brewster had a rematch in 2007, which Wlad avenged this loss by decisive TKO win. That was an important win for him and since about 2006, I would say Wlad's been pretty much invincible.
Wlad's had some losses (just as other heavyweight champs in history like Lewis, Ali, Dempsey and others), the worst of his career being the 2003 KO loss to Corrie Sanders, but actually his losses have made him a better fighter. Large part of the reason he is so good today is because he experienced those losses and used them to improve himself.
Wlad even stated that he was glad for his losses because they made him a better fighter, and he said he wouldn't be where he is today if it weren't for the losses. Since then, he's been easily the #1 heavyweight in the world for almost a decade now and is almost unbeatable.
Personally, I think it shows a great deal of character and championship mentality to come back from his losses to be #1 heavyweight in the world for almost a decade now. The simple fact of life is most boxers (even champions) lose fights at some point in their career. Guys like Rocky Marciano or Joe Calz are exceptions, not the rule!