This is the kind of night that has derailed many a highly-regarded boxer. Paul Williams best be careful he doesn’t add his name to that long, sad list.

Few people outside the immediate family and friends of Sergio Martinez believe this is likely on  tonight in Atlantic City and with good reason. Williams is considered one of the best pound-for-pound fighters in the world, a freak of nature who stands 6-1 with a reach of 82 inches yet can fight anywhere from 147 pounds to 160 pounds and maybe beyond.

He will have every physical advantage against Martinez, a junior middleweight who took this fight on a month’s notice after Williams’ second scheduled middleweight title fight with Kelly Pavlik fell through. What he won’t have is the mental edge, which on this kind of night can be more important than any other factor.

For Martinez this fight is an opportunity. It is a chance to put himself on the radar screen of mainstream boxing fans, something that hasn’t happened despite a 44-1-2 record and two recent appearances on HBO. Although Williams’ handlers insist he is the most avoided man in boxing, Martinez jumped at the chance because, for him, it is just that. A chance he has longed for. For Sergio Martinez, this is a welcomed night, an early Christmas present.

But for Paul Williams the situation is far different. This fight is a disappointment, one Williams will be reminded of when he walks into Boardwalk Hall in Atlantic City and sees the main room dark while he fights in the far smaller Adrian Phillips Ballroom because the promoters knew they would be lucky to fill what few seats they could squeeze in there with a main event like this one.

For months Williams (37-1, 27 KO) thought he was going to be in a Fight of the Year candidate, a career-changing event that could have made him a potential pay-per-view star. Oh, and he also was going to fighting for the middleweight title. Now he has this.

Pavlik kept saying he wanted to fight Williams and then kept pulling out with what became the longest running hand infection since before the invention of penicillin. Eventually Williams had to do something to get some work so he agreed to this fight after his handlers made clear they wanted no part of more high-profile opponents like Shane Mosley or Joshua Clottey, who are more welterweights these days than middleweights.

So Williams finds himself facing a guy he insists he’s taking seriously but who he frankly can’t be taking all that seriously. Williams is third on most pound-for-pound lists behind only Manny Pacquiao and Floyd Mayweather, Jr. Martinez is lucky if he’s third on most junior middleweight lists….and that is what makes him dangerous.

It will be far easier for Paul Williams to overlook Sergio Martinez than to overwhelm him. It is never easy fighting a southpaw, especially when you are left-handed yourself. It is also not easy fighting Martinez, who is 28-0-1 since being knocked out by Antonio Margarito (and who knows whether or not he had a horse shoe in his glove?) nearly 10 years ago.

The simple fact is Martinez is not as good a fighter or as gifted a one as Paul Williams but he is better than he gets credit for and good enough to pull off an upset on a night like this, when so many factors could come into play.

Not the least of them is Williams’ mindset. Every fighter says before the fight he’s ready, he’s focused, he’s not affected by the fact he’s not fighting the guy he thought he would fight for the money he thought he would make on the stage he thought he’d be on. Then the bell rings, he fights listlessly and after the bout says he couldn’t get up for it.

Time will tell if that is Paul Williams’ dilemma or if he rids himself of this latest problem with the kind of constant flurrying that has so many more recognizable names disinterested in facing him. Whatever happens it will be far more entertaining than the co-feature, which is a trip to the batting cage for Cris Arreola (27-1, 24 KO), the heavyweight from California who was beaten from pillar to post in his last outing by WBC champion Vitali Klitschko.

Arreola returns to the ring against Brian Minto (34-2, 21 KO). Brian Minto is a game guy. We move on.

If Williams does as expected he then needs to make a decision. He is unranked by the WBC, WBA or IBF despite the fact he’s considered to be among the top 10 pound-for-pound fighters in the world because since twice holding the welterweight title he hasn’t been in a weight division long enough to be ranked.

He says that’s because he can’t get any fights and hence has to take what he can find wherever he can find it. Perhaps but if he can’t find Kelly Pavlik any time soon he would be best served to go dominate one of those weight classes until there’s no one left to duck him.

Of course, before he does that he better remember to duck when Sergio Martinez walks out to greet him Saturday night or he may not have to worry for a while about anything else.