UFC 137: 6 Things to Expect in the Penn vs Diaz Main Event

Don't let the cancellation of GSP-Condit fool you.

Assuming someone from the Nick Diaz camp tells him when and where the fight is, UFC 137 still has a headliner-worthy fight.

When former Strikeforce welterweight champ Nick Diaz enters the octagon against UFC legend B.J. Penn, something memorable is bound to happen.

Here are six things to watch for in their upcoming bout.

1. Motivated B.J. Penn

From the outset of Penn's career, it has never been a lack of skills or talent that has been in question.

Penn has displayed a skill set that few have been able to match in the entire sport of MMA. The question has always been with his psyche.

Penn is a fighter who is very legacy-oriented. A win over Diaz could continue to build momentum toward an interesting run to end his career in the welterweight division.

Penn knows this, so expect to see him come out with a great attitude and the cardio to match.

2. Diaz Will Want a Street Fight

Nick Diaz was brought back to the UFC for one reason: To entertain.

From his wild, brawling style to his mid-fight trash talk, Diaz is wildly entertaining to watch. He knows that Penn has been broken before (GSP-Penn II), and while he doesn't have the smothering takedowns of GSP, he does have a unique style.

No fighter talks quite as much as Nick Diaz in the cage. When Penn lands his best stuff, Diaz will let him know he is not fazed. Despite all his skill on the ground, Diaz loves to stand and throw.

Diaz' stand-up style matches his attitude. While Diaz has game on the ground, he will look to make this as much of a slugfest as he can while using his impressive range to pick apart the smaller Penn.

3. Penn Will Be the Better Boxer

Much has been made of Nick Diaz' boxing ability, and he has been linked to several rumors that he considered switching over to boxing to face Jeff Lacy or Fernando Vargas.

Fans who expect to see Diaz have the upper hand in the boxing department should temper expectations, though. Penn is one of the best boxers in MMA.

Diaz' potential foray into the world of professional boxing was a joke. His wild, looping punching style would not hold up very well at the highest level of the sweet science. In fact, Penn would have a better chance at making a successful run as a professional boxer.

Penn has one of the most accurate lead jabs in UFC history and, when he throws punches, they are tight and generally on point. Diaz has power in both hands and is definitely a threat, but in terms of a pure boxing match, B.J. has the advantage.

However, this isn't a boxing match—it is MMA, and Penn's technique against Diaz' power will be an interesting subplot when the fight is standing.

4. Bottoms Up

As much as fans want to see these two slug it out, the fight could be just as interesting on the ground. Both of these guys are elite jiu-jitsu practitioners who feel as comfortable in guard on the bottom as they do controlling top position.

Penn has been known to beat up guys in rubber guard and has impressive submission victories, including wins over Matt Hughes, Kenny Florian, Joe Stevenson and Jens Pulver.

Diaz is no slouch when it comes to submission either. He is 8-0 in fights that end by submission.

While neither of these guys has been submitted, the back and forth in the grappling department could be just as close and entertaining as the exchanges on the feet.

5. A Very Interested Dana White

Dana White loves a good old-fashioned scrap. He tends to reward those who throw caution to the wind and go for the finish.

Both Penn and Diaz will lay it all out there and try to finish each other, and White will surely be looking to reward whomever comes out on top.

Should Diaz find a way to win, it's all but guaranteed he will get an immediate shot at the belt. Yes, he already had one shot taken away for not showing up to press conferences, and he was extremely late to a conference call even after that incident.

However, all will be forgiven if he puts on a show and wins against Penn.

For Penn, a title shot may not be imminent, as it would be extraordinarily hard to sell a trilogy fight with GSP, and a return to lightweight to fight Frankie Edgar a third time is not really an option either. However, what Penn could earn with a win is the right to choose his next fight and settle the score with new-found rival Jon Fitch, whom he fought to a draw at UFC 127.

6. Fight of the Night

The UFC could not have asked for a better fight to replace a title fight in the main event slot.

There is just no way this fight is boring. Both Penn and Diaz have a lot on the line and figure to do whatever it takes to get the win. Neither guy is a stranger to putting on great fights for the fans. This one is a lock for fight-of-the-night honors.

As with any fight between two guys with the kind of power Penn and Diaz possess, the chance for a quick finish is always there. A quick knockout is the only way this fight isn't an instant classic.

An instant classic or a sudden knockout? That's what makes a great headliner and makes this fight the ultimate win-win for fans.