By Keith Idec

Chazz Witherspoon’s window of opportunity is almost closed.

The college-educated heavyweight knows if he doesn’t defeat Seth Mitchell on Saturday night in Atlantic City that he’ll have wasted a perfect chance to completely change the course of his seven-year pro career. The Paulsboro, N.J., native doesn’t agree with placing so much emphasis on one bout, but he accepts the reality of what awaits him at Boardwalk Hall in the opener of an HBO “World Championship Boxing” doubleheader (10:15 p.m. EDT).

“I know a win against Seth would revitalize my career,” said Witherspoon, a second cousin of former heavyweight champion Tim Witherspoon. “But I always speak to the fact that boxing is one of the only sports that as soon as you lose one fight or two fights it’s like your career is over.

“Kobe Bryant can go out and have five points in one game and then the next game go out and drop 40, 50 points, and he’s still Kobe Bryant. But in boxing, one, two losses, your career is done. I don't really understand that, but I know [beating Mitchell will] revive my career because in boxing you’re only as good as your last win. So it would do tremendous things for my career. It would put my name back in the mix.”

A ninth-round technical knockout loss to Tony Thompson in December 2009 took Witherspoon (30-2, 22 KOs) out of the mix. Washington, D.C.’s Thompson (36-2, 24 KOs) used that victory as a springboard toward a second shot at Wladimir Klitschko this summer, but Witherspoon has been relegated to four low-profile fights against journeymen since suffering that defeat, also in Atlantic City.

The 30-year-old Witherspoon’s only other loss came against Chris Arreola in June 2008. Arreola (35-2, 30 KOs) won their bout by disqualification in Memphis, Tenn., because one of Witherspoon’s corner men stepped on the ring apron and came into the ring before the end of the third round. Arreola appeared, however, to be on his way to knocking out a wobbled Witherspoon, who had been dropped twice in the third.

Nevertheless, Witherspoon owns an experience edge over Mitchell, a 29-year-old former Michigan State linebacker that took up the sport less than six years ago.

“I do know that this is one of the times, one of the few times, that I have more experience than the person I’m getting in the ring with,” said Witherspoon, who was an alternate on the 2004 U.S. Olympic Boxing Team. “So I’m cognizant of that. But as far as thinking Seth doesn’t have what it takes to be here, it’s obvious he does because we’re here. I'm actually the underdog in this fight. I’m not expected to win this fight. He’s expected to win this fight.”

Oscar De La Hoya’s Golden Boy Promotions is grooming Mitchell, of Brandywine, Md., for a run at one of the Klitschko brothers in a division devoid of formidable, marketable American contenders. Witherspoon is regarded as a respectable but beatable opponent.

“The one way that I do look at it is that there’s no pressure on me,” Witherspoon said. “So, I mean, I like that because most of the times when I’m fighting I’m expected to win. So the pressure’s on me to make the fight look good and make the fight look a certain way, do all these things. That pressure’s not on me. So it allows me just to be me and fight. So I have a freedom from that standpoint.”

Keith Idec covers boxing for The Record and Herald News, of Woodland Park, N.J., and BoxingScene.com.