(REUTERS)-World heavyweight champion Vladimir Klitschko knocked out Bulgarian challenger Kubrat Pulev with a fierce left hook in the fifth round on Saturday to retain his IBF title and end his opponent’s unbeaten record.The 38-year-old Klitschko, who also holds the WBO, IBO and WBA titles, knocked down the 33-year-old twice in the opening round before Pulev was again floored in the third, sent sprawling by a thundering left hook.
Another giant left hook finished the job in round five with Pulev suffering his first loss after 20 wins.
Klitschko has improved his record to 63 wins out of his 66 fights with 54 knockouts.