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 his own. After the Johnson bout, Klitschko's camp began negotiations for a potential fight with former WBA Champion Nikolai Valuev, but the match failed to materialize due to economic disagreements. On 29 May 2010, Vitali Klitschko defeated Polish heavyweight contender Albert Sosnowski by KO at 2:30 in round 10 of 12. Sosnowski was knocked down by a right hand in the 10th round, prompting referee Jay Nady to immediately wave off the fight. The fight took place at Veltins-Arena, Gelsenkirchen, Nordrhein-Westfalen, Germany. Vitali Klitschko weighed in at 112 kg (247 lbs), while Sosnowski weighed in at 110 kg (242.5 lbs).