 Krzysztof Zimnoch once defeated the current heavyweight boxing champion, who has held his title since what year?
Krzysztof Zimnoch:  He holds an amateur win over current WBC heavyweight champion Deontay Wilder. Deontay Wilder:  He has held the WBC heavyweight title since 2015, and in doing so became the first American world heavyweight champion in nine years, which was the longest period of time in boxing history without an American heavyweight champion.
i don't know