WBA heavyweight champion Ruslan Chagaev tore his Achilles' tendon while sparring this week, forcing the cancellation of his title rematch against Nikolai Valuev in Germany on July 5. Chagaev (24-0-1, 17 KOs) completely tore his tendon during the next-to-last round of his final sparring session Thursday, Universum Box-Promotion announced on its Web site. Chagaev has pulled out of three fights with illness or injury since winning his title in April 2007 with a majority decision over Valuev (48-1, 34 KOs), a 7-foot, 320-pound Russian. Their second meeting already was postponed from May 31 to July when Chagaev, a native of Uzbekistan who lives in Germany, came down with a viral infection.