They share little in common other than an extraordinary ability to cause harm in a boxing ring. Between them, Gennady Golovkin and Roman Gonzalez have won all 78 of their professional fights, 69 of them by knockout.

One is a heavily muscled middleweight from an old Soviet bloc country who, despite struggles with the language, has a charismatic and outgoing personality. He has a magnetism that draws people to him like some kind of pugilistic pied piper.

The other is a tiny man, one who could easily be mistaken for a jockey. He's soft spoken and reserved and deeply religious.

They're both, though, regarded among the top three fighters in the world, and are Nos. 1-2 by many reputable boxing experts.

Golovkin is the WBA/IBF/interim WBC middleweight champion, who is 34-0 with 31 knockouts in a dozen years as a pro. Gonzalez is the WBC flyweight champion who is 44-0 with 38 knockouts. And while it may seem a heresy, he may just be a more gifted fighter than his late, great mentor, Hall of Famer Alexis Arguello.

On Saturday, they appear on the same card for the third bout in a row, headlining an HBO doubleheader that because of the epic mismatches on paper would be totally devoid of interest were it not for their individual greatness.

Gonzalez faces McWilliams Arroyo for the flyweight belt in the opener at what figures to be a sold out Forum in Inglewood, Calif. In the main event, Golovkin will defend his belts against Dominic Wade.

Depending on where you look, Gonzalez is better than a 25-1 favorite to defeat Arroyo, while Golovkin is a 15-1 favorite to defeat Wade.

Normally, that would lead to a lot of carping about the poor matchmaking, but that hasn't been the case for this show.

Golovkin and Gonzalez are so great, it's almost as if boxing fans feel it's a privilege to watch them do their destructive work.

"When you can put the two best fighters in the world on the same card, it gets people excited," promoter Tom Loeffler said.

Curiously, the fighters are into it, as well. Golovkin said he enjoys watching Gonzalez ply his trade, while Gonzalez called Golovkin a role model for boxers.

Golovkin, 34, has gotten the star treatment for years now, essentially covering President Obama's second term. But while Obama's fortunes have gone up and down and perception of his success depends greatly on one's party affiliation, such is not the case with Golovkin.

He's pretty much been boffo every time out, coming in with lofty expectations and managing to exceed them ever since he's come to North America.

"Gennady is never satisfied," trainer Abel Sanchez said. "He's always in search of that next level and he is so determined to get everything right."

View photos Roman Gonzalez is a legend in his native Nicaragua. (AP) More

Gonzalez called it an honor to share a card with Golovkin. Gonzalez, 28, is an icon in his native Nicaragua, and has held a major world title for more than seven years.

Since he first competed for a world championship, he's won 24 in a row with 20 by knockout, though that includes seven non-title bouts.

His precision in the ring is extraordinary and his defense almost impregnable. He rarely gets hit cleanly (even though he's an extremely aggressive fighter) because he understands angles, how to control the distance and he walks opponents into his punches.

He's one of the most accomplished fighters in the sport, but if you think it would be hard to impress him, you'd be wrong. He raves about Golovkin.

Story continues