HAMBURG, Germany — Undefeated Alexander Povetkin of Russia retained his WBA heavyweight title with a second-round technical knockout of American challenger Hasim Rahman Saturday. After a cagey first round, Povetkin exploded into life in the next, delivering a series of blows to which the 39-year-old former WBC, IBF and IBO champion had no response. Referee Gustavo Padilla of Panama had no option but to call it off 1 minute, 36 seconds into the round with Povetkin able to pick his shots at will. Rahman dropped to 50-8-2 (41 KOs) after his first bout since June 2011. — Reuters