Hasim Rahman is the perfect opponent for heavyweight champion Wladimir Klitschko. He looks more fearsome than he is.

Two weeks before Christmas, the unified IBF and WBO champion will get his first present of the holiday season at the SAP Arena in Mannheim, Germany when he gets into the ring with a 36-year-old, jet lagged Rahman, who is the polar opposite of the injured original opponent he is replacing.

With only 16 professional fights and none against formidable opposition, Alexander Povetkin may have been the IBF’s mandatory challenger but he was not likely to challenge Klitschko for long. Povetkin lacked experience, pedigree and, frankly, the punching power to stand tall with the 6-6 Klitschko for very long.

Rahman, on the other hand, has legitimate one-punch power and a lot of experience against top shelf heavyweights, if such a thing still exists in the present dismal climate. What he doesn’t have is a decent work ethic in training, a decent chin and, most importantly, a decent heart for the business he’s in. As Joe Frazier once put it about an opponent he did not particularly respect, “His heart pumps Kool-Aid.’’

Rahman’s pumps blood but not much resolve, as he showed in his last fight when he quit on his stool after being cut by former middleweight champion James Toney. The opinion of most in boxing was that it was a Monty Python kind of cut (“Only a flesh wound’’) yet Rahman chose to retire, ultimately getting a no contest in a fight he should have lost.

At 36, Rahman (45-6-2, 36 KO) now seems to be the classic journeyman in search of a payday. Serendipity brought him this one Saturday night on HBO. After Povetkin sustained a foot injury and pulled out on short notice a scramble to find a replacement began and there was the always affable and agreeable Rahman and hence a title shot was born despite the fact he had done nothing to earn it except still being breathing and in a gym at the time.

The IBF has said it will continue to maintain Povetkin as the mandatory challenger but Klitschko was allowed to go forward with what now seems likely to be a cautiously boring affair for a number of rounds with Klitschko (51-3, 45 KO) using his long jab to stab at Rahman while seldom fully engaging with him until fatigue starts to set in. When it does, Rahman figures to fold his tent or have it folded up for him by the stiff jab/straight right hand combination Klitschko has used to erase a wide number of opponents.

Yet there remains one mystery that brings intrigue to this match. Or maybe it is two. The one-punch knockout power of Rahman, which first brought him the heavyweight title seven years ago when he stunned Lennox Lewis by knocking him stiff in Johannesburg, South Africa, is part of that mystery.

The other part is the designated landing strip for such punches – the formerly failed chin of Klitschko. The champion has been stopped three times (by Ross Purrity, Corrie Sanders and Lamon Brewster) and in each case Klitschko claimed he’d been hit with fatigue, a problem he insists he has since overcome. He was perhaps fatigued in those fights by the time they were stopped but that didn’t seem to be a problem until he got hit on the chin a few too many times.

That is why the words of his trainer, affable Emanuel Steward, carry some sense of veiled foreboding with them.

“We take him very seriously,’’ Steward said of Rahman this week. “We consider him more dangerous than Povetkin. He is the strongest one-punch puncher Wladimir has ever faced.’’

If he is, then Povetkin is in danger of not having Klitschko around to challenge next year. Yet the truth seems to be somewhat different. Rahman is dangerous because he can punch with unusual authority if he lands and Klitschko’s chin has proven suspect when reached by someone with power but being dangerous does not necessarily make you dangerous. The opponent will have something to say about that and in this case, the 6-foot-6 Klitschko appears to have the physical skills and size to hold off a faded Rahman until his resolve begins to wane, as it so often has since losing the world title a second time.

When Rahman’s hope begin to fade and he begins to fatigue and feel some pain himself, then and only then will the ultra-conservative Klitschko move in for the kill. When he does, what falls seems likely to be a fistic formality,

“I am not going to underestimate him in any way,’’ Klitschko said in Mannheim. “This is his last chance. I expect a challenge from Hasim Rahman because he’s up against the strongest man in the heavyweight division and three titles are at stake.

“Of course I expect I’ll be more than he can handle – like it is with everyone I face.’’

That seems a stretch of self-indulgence but it is difficult to refute Klitschko’s take on this fight. He could, as he has before, get lazy or become unfocused and get caught with a bomb from across the unseen horizon that dethrones him but the more likely scenario is that Klitschko out boxes and outhustles Rahman for the first half of the match, beating him to the punch and ever more steadily hurting him with big combinations until Rahman collapses as much from indifference as anything else.

Once that corrosive process begins, the fight is over, yet Rahman still will have one thing going for him besides power. He will have Klitschko’s on-going fear of firepower, a concern that while well placed considering his past has often made him seem a very reluctant dragon himself.

To push that psychological advantage, Rahman will first have to push himself and then push Klitschko as well. Yawning and nearly half asleep at a Monday press conference in Mannheim, Hasim Rahman did not appear to anyone in attendance to be ready to do that, so the likelihood is that he is looking at this fight the same way Klitschko is – as an early Christmas present, an unexpected bonus at the end of the year and nothing more.