MANNHEIM, Germany — Wladimir Klitschko believes Hasim Rahman is a better opponent than the man he replaced, unbeaten Russian Alexander Povetkin.

Rahman, a former two-time world heavyweight champ-ion, agreed to fight Klitschko only last month after Povetkin pulled out with an ankle injury.

Klitschko was happy, and wary, of giving Rahman another shot at his IBF heavyweight title today at SAP-Arena.

“Wladimir is very focused. He realizes how dangerous a puncher Hasim is,” said his trainer Emanuel Steward. “We take him very seriously. We consider him more dangerous than Povetkin.

“We expect a very tough fight. Wladimir considers him the most dangerous one-punch fighter he’s ever faced.”

It will be Klitschko’s sixth defense of the IBF title he won against Chris Byrd when it was vacant in April 2006. This will be his third fight of the year, after beating Sultan Ibragimov by unanimous decision in February and knocking out Tony Thompson in July.

The Ukrainian-born fighter takes a 3½-inch height advantage against the 6-foot-6 Rahman. Klitschko’s chin remained suspect after knockdowns by Ross Puritty, Corrie Sanders and Lamon Brewster.

“I am not going to underestimate him in any way,” said Klitschko (51-3, 45 KOs). “I am going to do my job the best way I can and I will try to do it quickly.”

Rahman arrived in Germany from the United States on Monday and looked trim and impressive in his only public training session. Rahman weighed in at 253.5 pounds on Friday, with Klitschko at 244.7 pounds.

“He is very fit, very well prepared,” Rahman’s manager Steve Nelson said. “He’s in tremendous shape.”

Rahman said he had sparred more than 100 rounds.

“I know he is extremely strong and quick,” Rahman said. “I have to be ready to take punishment and to dish it out. I am very fit and well prepared. This here is Klitschko land now. On Saturday, it will be Rahman land.”

Steward was in Lennox Lewis’ corner when Rahman (45-2-6, 36 KOs) stunned him in April 2001 for the WBC and IBF titles, but lost them to Lewis seven months later. When Klitschko’s older brother Vitali retired, Rahman won the vacant WBC belt in 2005 and held it for a year until losing to Oleg Maskaev.

His last fight in July against James Toney was ruled a no-contest after Rahman was cut.

“This is his last chance to be a world champion again,” Klitschko said. “I expect a real challenge.”

Rahman wasn’t fazed by the record of Klitschko, who hasn’t lost in more than four years.

“Yes, he is the best, but I want to be the best, and to be the best you have to beat the best,” Rahman said.