Claim: Wladimir Klitschko has fought in 19 heavyweight title fights.
Evidence: Overall , he became the second-longest reigning heavyweight champion of all time , and has the second-most successful title defenses total of any heavyweight boxer with 23 -LRB- including his initial reign as WBO champion -RRB- , behind Joe Louis -LRB- 25 -RRB- and ahead of Larry Holmes -LRB- 20 -RRB- and Muhammad Ali -LRB- 19 -RRB-.