Vladimir Klitschko successfully defended his IBF heavyweight crown by stopping Hasim Rahman in the seventh round at SAP Arena on Saturday. Klitschko hit the shorter, older and heavier Rahman at will throughout, and after landing a left-right-left combination against the cornered American, referee Tony Weeks stepped in to end the contest 44 seconds into the round. Rahman didn't appear upset. Klitschko had knocked down Rahman in the previous round with successive left hooks in the one-sided bout before more than 10,000 spectators. The technical knockout in Klitchsko's sixth defense of the IBF belt - and third this year - improved the Ukrainian-born fighter to 52-3 with 46 KOs. He hasn't lost in more than four years. Rahman, the two-time heavyweight champion who stepped in as a replacement opponent only last month, struggled to get inside the taller Klitschko's reach, and dropped to 45-7-2. “He fought a very smart, intelligent fight,” said Klitschko's trainer, Emanuel Steward. “Vladimir was very smart not to throw too many punches and to be very patient and to work behind his left jab.” From the beginning, it soon became apparent that Rahman was struggling to overcome the 9-centimeter (3½-inch) height advantage enjoyed by the champion. Rahman had to lean in drastically to find openings, and Klitschko easily fended off his few punches. Rahman did little more than lean on the ropes for a time and guard his face. He looked reinvigorated in the fourth round, using his whole torso to make ambitious attacks, often connecting with Klitschko's body. But he rarely landed blows above Klitschko's shoulders, and the consequences were clear when Klitschko dropped Rahman early in the sixth with two hard lefts to the side of his head. Rahman got up but spent the remainder of the round in the corner, taking a sustained beating. Another flurry at the opening of the seventh ended 36-year-old Rahman's challenge. Klitschko, 32, also retained the minor WBO and IBO belts. Klitschko was originally scheduled to face Alexander Povetkin (16-0), but the Russian pulled out with an ankle injury. Klitschko believed there was enough rising talent in the division to be challenged, citing Povetkin, fellow Russian Nikolai Valuev, and American Cristobal Arreola. He also mentioned British boxer David Haye, who monopolized the post-fight press conference with a challenge to Klitschko's older brother, Vitali, the WBC champion. Earlier, former heavyweight champion Riddick Bowe made a successful comeback at the same venue after 3-1/2 years out of the ring. Despite looking overweight, 41-year-old Bowe beat German Gene Pukall on points on the undercard.