Chagaev 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. 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.

Chagaev has made just one title defense, beating Matt Skelton in January. Chagaev will need surgery, but Dr. Michael Ehnert believes the heavyweight could recover in time to fight again in 2008, Universum said.

The rest of Universum’s card in Hannover, Germany, will still go on, with WBA middleweight champion Felix Sturm fighting American Randy Griffin in the new headline bout.