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WBO cruiserweight champion Marco Huck of Germany is moving up to the heavyweight level against undefeated Alexander Povetkin.

He'll step into the ring 20 pounds lighter (209) than the Russian, who will defend his WBA title on Saturday night.

"In the end it won't be my weight that's decisive, but my punch," Huck said.

Povetkin will make his second defense of the title he claimed by defeating Ruslan Chagaev last August.

It had been Wladimir Klitschko's title following the Ukrainian's victory over David Haye the month before, but was declared vacant when the WBA elevated Klitschko to "super champion" status.

The Yugoslav-born Huck is 34-1 (25 KOs) heading into the bout at the Porsche Arena.

"Povetkin is good, but I can beat him," Huck said. "We once did sparring together and he has bad memories of me. On Saturday, I will be the new champ. He is going down."

Povetkin, whose record of 23 wins includes 16 knockouts, was unfazed by Huck's show of confidence.

"At first I was surprised about Huck's challenge because he has never fought at heavyweight before," he said. "But I am happy to defend my title against anybody out there. I am in great shape and I will win."

It will be the Russian's first bout without respected American coach Teddy Atlas since 2009. But Povetkin said training in his home city of Chekhov with new coach Alexander Zimin was "very good."

"There is a good chemistry between us and we get along very well," Povetkin said.

Zimin believes his fighter is "20 to 30 percent stronger than in his last fight," an eighth-round knockout of American challenger Cedric Boswell.

"But the best is yet to come. He has got great potential," he added, looking ahead to a possible bout against one of the Klitschko brothers, who have a stranglehold on the heavyweight division.

Older brother Vitali Klitschko retained his WBC title by beating British boxer Dereck Chisora on points last weekend in Munich. Wladimir will defend his "super" WBA belt, and his IBF, WBO, IBO titles, against Jean-Marc Mormeck of France in Duesseldorf next weekend.