There are two types of fuel that fire fights -- competitive or personal. The competitive juice is the stuff that makes fighters want be the best. The personal type attaches memory and feeling to that goal. That fuel can sustain fighters at the point of burnout, and it can also rob them of energy when they most need it.
When it comes to Saturday's clash between middleweight champ Anderson Silva (27-4) and Vitor Belfort (19-8), you can believe the fighters, who tell us that they are fueled by the former -- a desire for greatness, to be considered the best in the world.
Or you can believe the promoter of the pay-per-view event they headline, Dana White, who says a deep enmity burns between the two, and it's been glossed over in the run-up to UFC 126.
Or you can believe, as I do, that the answer was given Wednesday when the two engaged in a staredown at a pre-fight news conference at the Mandalay Bay Events Center in Las Vegas. A non-verbal answer, as it so often is, given away by the face and body language of Silva.
The middleweight champ wore rock-star glasses and a look of disinterest. But when he took off those glasses and squared up with Belfort, that look transformed from disinterest into a seething stare issued whisper-close to the challenger. Meanwhile, he slowly rocked back and forth, as if ready to take a stance and fire off a kick.
It was a look that said, "You wanted this fight? Now you've got it." A look not too different from the one he gave trash-talker Chael Sonnen two days before their meeting at UFC 117 last August.
Need further proof of bad blood? Click through the pile of online interviews Silva has given about this matchup, which has floated in the ether for more than a year but been delayed by injuries, scheduling and who knows what else. Silva's anger reads loud and clear. He trained with fellow Brazilian Belfort and welcomed him into his extended family. Then, Belfort turned his back on the family by accepting a title shot. Career over family. Not cool.
So don't believe Silva for a second when he says Saturday's fight is "normal." He's been asked about bad blood far too much. Now, it's like a fly he swats away. It's too draining to retrace those feelings, and besides, he's been around long enough to know that they're ultimately being exploited for business gain.
And sometimes, just sometimes, you get the feeling that Silva resents the "commerce" side of art vs. commerce.
"We're both employees of the UFC, and this is our job to get in there and fight and put on a show for everybody," the middleweight champ said Thursday through his manager and translator, Ed Soares. "I have nothing personal against Vitor."
White doesn't believe it. Rivaling the UFC executive's talent for hyperbole is a nose for baloney. Or, in this case, "30 minutes of bull----," as he told reporters after Wednesday's news conference. In addition to the competitive stakes for the two -- a second UFC title for Belfort, a 14th consecutive win and eighth straight title defense for the champion -- is Silva's desire to exact revenge.
That desire doesn't seem to be shared by Belfort. He said he sees right through Silva's look.
"His actions speak louder than his words," the one-time light heavyweight champion said. "I think he respects me. I just think he wears the mask, trying to intimidate me. He can see it in my eyes. I'm on fire. I'm not getting intimidated by anyone."
Here's the problem in getting to the bottom of all this: Even if feelings boil beneath the surface, the fighters are not going to let them crack a facade built over many years to conceal any signs of weakness. And emotions universally are looked at as a disadvantage in a fight. They may keep you going, but they'll gas you out.
So we have to read between the lines (or just look on the Internet). Would it be more entertaining for the rest of us to see an encounter session? You bet. But we don't have to get in the cage and fight five rounds for a UFC title.
Silva may have an outmoded view of training relationships in today's fight game, or maybe he's a little bit purer that most in the way he looks at it -- when you go into battle with a team, that team stays on your side. Maybe Belfort is putting personal gain above the people who helped make him great.
Who knows. It doesn't really matter what's fueling these two, as long as it propels a great fight. Maybe they'll hug it out afterward. It looks needed.