Vitali Klitschko retained his WBC heavyweight title with a unanimous decision over previously unbeaten Kevin Johnson of the United States Saturday. The 38-year-old Klitschko kept Johnson against the ropes for much of the fight but landed few heavy shots to hurt the 30-year-old challenger. “I would have preferred a knockout but I'm happy because I won all 12 rounds,” Klitschko said. “He's not easy to hit.” Johnson proved a durable opponent and did his best work with counterattacking straight left jabs, though without managing to rock Klitschko who has never taken a standing count in his career. “When I first met Vitali I told him, ‘You won't knock me out.' It wasn't a hard fight,” Johnson said. “There are things we need to work on and we're going to go home to the gym and polish them up.” Klitschko (39-2, 37 KOs) was making a third successful defense of the belt he reclaimed in October last year after a four-year break to recover from injuries. He opted to take the fight just 11 weeks after beating Cris Arreola, another unbeaten American who did not come out for the 11th round of their bout in Los Angeles. Johnson, the WBC's sixth-ranked contender, experienced his first professional defeat in his 24th fight. At 2.02-meters and 112 kgs, Klitschko took a size advantage of 11 centimeters and 2kg into the ring. Johnson opted for defensive tactics, inviting the champion from Ukraine in the second round to come at him. Klitschko aimed mostly head shots but a succession of overhand rights found Johnson turning away in defense. The champion's right cheek was marked in the fourth round, and Johnson connected with a left hook in the sixth. But Johnson failed to mount many combinations and Klitschko kept winning rounds with steady jabs, more big rights and an occasional straight left. The fight heated up in the 11th when Klitschko responded to Johnson's taunting hands-spread gesture with a flurry of blows. In the final round, Johnson pointed at his chin to goad Klitschko into another attack, and the bout ended with the American finally trading punches in the center of the ring. The two squared up after the bell and Johnson was ushered back to his corner by Klitschko's young brother Wladimir, the IBF and WBO champion who works in Vitali's corner. Darchinyan flattens Rojas Australia's Vic Darchinyan knocked out Mexico's Tomas Rojas in the second round Saturday to retain his World Boxing Council and World Boxing Association super flyweight titles in Rancho Mirage, California. The Armenian-born Aussie fighter flattened Rojas after two minutes and 54 seconds of the second round, improving to 33-2 with one drawn by taking his 27th victory inside the distance in the matchup of southpaw stars. Rojas fell to 32-11 after his first loss in more than two years. In the card's other main fight, Timothy Bradley won a unanimous decision over Lamont Peterson in a matchup of US unbeatens to keep his World Boxing Organization junior welterweight title. Bradley improved to 25-0 on judges' scores of 118-110, 119-108 and 120-107. Peterson fell to 27