Wladimir Klitschko Universum Box-Promotion in Hamburg under the tutelage of Fritz Sdunek, often being featured on fight cards alongside his elder brother Vitali. After building an undefeated record of 24–0 with 22 KOs, he suffered his first loss to 24–13–1 Ross Puritty, in what was Klitschko's first and only professional fight in Ukraine. Puritty forced Klitschko, who had at that time not gone beyond 8 rounds, to punch himself out. Klitschko began to be overwhelmed in the 10th round and went down twice but was allowed to continue. At the start of the 11th round, with Puritty continuing to land hard punches,
Vitali Klitschko technical knockout. Negotiations for a 6 December rematch began. After negotiations collapsed, Vitali defeated Kirk Johnson in a WBC Eliminator bout on 6 December date, setting up a mandatory rematch with Lewis. In January 2004, the WBC announced that it would strip Lewis of the belt if he let pass a 15 March deadline to sign for a rematch with Vitali. Shortly thereafter, Lewis announced his retirement and vacated the title. For years after this fight, Klitschko would still occasionally call out Lewis, despite the fact that Lewis has been retired since early 2004, for a rematch. Around this time