BetUS Sportsbook bettors, as well as most people in the boxing world, will be watching closely this weekend when Juan Manuel Marquez of Mexico takes his maiden voyage in the 135-pound division against Cuba's Joel Casamayor. The two will do battle on Saturday, September 13 at the MGM Grand Garden in Las Vegas in a bout that is scheduled for 12 rounds.

BetUS Boxing Betting Odds

Lightweights - 12 Rounds
September 13 - Las Vegas
JUAN MANUEL MARQUEZ -350
JOEL CASAMAYOR +250

OVER 9.5 ROUNDS -400
UNDER 9.5 ROUNDS +300

For betting purposes, let's take a look at the contestants:

MARQUEZ (48-4-1, 35 KO's), the -350 favorite in the BetUS boxing betting odds, has overcome a loss in his pro debut to have quite a storied career. After the initial defeat, he went undefeated for a period of over six years before losing a decision to Freddie Norwood in September of '99 for the WBA featherweight title. Marquez made good on an attempt to win the WBA and IBF world titles in November of 2003 when he won a technical decision over Derrick Gainer, then boxed a draw with Manny Pacquiao in his very next fight. In March of '04, he went to Indonesia and lost a decision to Chris John in what was a controversial result.

But he came back five months later to stop Terdsak Jandaeng in seven rounds to win the vacant WBO featherweight crown. Marquez then made the jump to the 130-pound division and beat Marco Antonio Barrera for the WBC championship. Marquez had a spirited effort against Rocky Juarez last November and won a clear-cut unanimous decision by six, eight and 12 points on the judges' cards. In his last fight, Marquez lost a split decision in the widely-anticipated rematch with Pacquiao.

CASAMAYOR (36-3-1, 22 KO's), the +250 underdog at BetUS, was the bantamweight gold medalist at the 1992 Olympics in Barcelona. After making his pro debut in September of 1996, he was brought along relatively carefully, facing few serious threats until he decisioned Jose Luis Noyola for the NABF 130-pound title in January '99. he won the interim WBA crown five months later by beating Antonio Hernandez. Casamayor won six more title fights before losing a decision to Acelino Freitas in January of 2002 that was for a unified WBA-WBO title. His trilogy with the late Diego Corrales was especially interesting; he stopped Corrales in six rounds in October 2004, lost a split decision to him one fight later, then won a split decision in October of 2006 to win the WBC lightweight title over Corrales, who has pushed himself into a corner by not making weight. In his last bout, Casamayor won the interim WBO title by stopping rough-and-ready Michael Katsidis this past May 22.

I believe Marquez to be one of those fighters who could be tremendous in any era. He is so technically efficient, and even when he doesn't fight as well as he should, as some people felt when he fought Juarez, he still did a polished job. And let's not forget that Juarez, though not a slickster, was a dangerous puncher nonetheless, and Marquez still chopped him down pretty good.

Casamayor has been through some close calls of late. When he beat Corrales and Joe Armando Santa Cruz, it was by split decision. Before he stopped Katsidis, he was behind by a point on two of the judges' scorecards.

I don't sense that Casamayor is quite as good a fighter as Marquez, but I see a few things here that might cause some problems for Marquez. One is that Casamayor is a southpaw, and although Pacquaio represented a different style of southpaw, coming from the other side is always something that is difficult for the opponent to navigate, especially if you have talent. Casamayor has a chance to land a high percentage of his straight right hands.

And there is a question of style when it comes to the way the pattern of this fight is going to play out. Marquez would like to so some counter-punching, but Casamayor is going to force him to be more straight-forward and aggressive, and if that happens Casamayor is going to exploit an edge in defense and land those counter-punches when Marquez finds himself out of position.

Casamayor has also been a lightweight for about the last four years, while Marquez hasn't fought at that weight yet. In fact, less than two years ago, he was a featherweight, and in boxing terms, these are big leaps. Neither guy is getting any younger - Marquez is 35, and Casamayor is 37 - but I think Casamayor might be the guy who's got less wear and tear on his body.

Maybe I'm wrong, but this fight is probably somewhat closer than the numbers indicate. Therefore, I would declare some value on the underdog. That means Casamayor as the +250 underdog in the BetUS boxing betting odds.

JAY'S PLAY: CASAMAYOR TO WIN (+250) **
(Graded on a scale of 1-4 stars)

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(Charles Jay of www.ebookies.com is a former manager, matchmaker and color commentator in professional boxing. He currently pulls no punches in the BetUS Locker Room)