"Straight down the middle, that's it!" shouts Diaz's boxing coach, Richard Perez.
With his snow-white hair and gregarious disposition, Perez is a little like Santa Claus in a sleeveless t-shirt. He leans against the cage and shouts more encouragement than instruction as Diaz bulls his way forward against a series of smaller, quicker sparring partners. They come bouncing in and go dragging out in rotating shifts. Perez tells them to circle. That's what "this guy" will do, he says.
Everyone in Diaz's gym on School Street in Lodi's quaint little downtown district knows who "this guy" is, but no one says his name. Not once. They don't need to.
This Saturday night in San Jose, Diaz again meets K.J. Noons, the last person to put a loss on his record. The evidence of Diaz's first meeting with Noons is still etched in his face. That thick line of scar tissue carved into his brow, the way the skin around his eyes seems to sag in a perpetually weary expression, that was at least partially Noons' doing.
That's what stopped the fight, at least. It was the cuts that gave Diaz his first loss since his exit from the UFC in 2006. The fact that he hasn't lost since, he points out, is evidence that Noons was fortunate enough to catch him at a difficult time in his career.
"I had a lot of issues then," Diaz says. "I had problems with [cuts] before that, and I had staph, had to go to the hospital, I just had a hard couple of years. I had so many fights."
When he fought Noons in November of 2007, Diaz had fought eight times in 21 months. He'd just come off a decision victory over Mike Aina in Hawaii and had to be rushed to the hospital with a staph infection upon his return.
Less than two months later, he fought Noons for the vacant Elite XC lightweight title, only to be stopped by the cageside doctor after Noons put his boxing skills to work and sliced up Diaz's face for most of the first round.
If Diaz is concerned about avoiding blows when the two meet again in Strikeforce on October 9, you wouldn't know it from the way he's training just a week out from his first title defense.
Each round goes more or less the same: Diaz storms forward into increasingly confident punch combos from his opposition, who all seem pleasantly surprised that they're able to hit him at all. The first minute belongs to the sparring partners. This isn't so bad, you can almost hear them thinking. I'm hanging with Nick freaking Diaz.
Then it's Diaz's turn. He cranks up the pace and starts thumping them to the body or snapping their heads back with counter hooks. They fade, and he surges. Suddenly the cage starts to seem too small. There's nowhere to hide. Diaz is barely even breathing hard.
After an especially intense round, one beleaguered sparring partner pulls off his headgear and grabs a seat in the open doorway to catch the cool afternoon breeze coming in. His nose is swollen and his eyes are watering. The look on his face says, Maybe if I remain very still, he won't ask me to go another round.
He's spent a lot of time working with boxers who can mimic Noons' style. He even did some work with undefeated WBA super middleweight champ Andre Ward in the lead-up to this fight. The message is clear: Diaz isn't just looking to get this fight to the mat, in part because he's not nearly as impressed with Noons' boxing skills as Noons seems to be.
He is willing to give his opponent credit for one thing, though.
"[Noons] is picking really smart fights," Diaz says. "I'll give him that. He's fighting only stand-up fighters, even like myself. He doesn't want to fight anyone who just wants to take him down. If he fights a real serious wrestler, he won't survive the way I can. If I get taken down you can't finish me, but if he gets taken down you can just lay on him. I mean, I'd imagine. I don't really know because I haven't seen him do sh-t."
This is the Diaz most people know. The brash, angry kid giving the world the middle finger, usually with both hands. He doesn't play well with others. He doesn't smile for the cameras. He's by no means guaranteed to show up for interviews or pre-fight conference calls.
"I am honestly too busy training for that sort of thing," says Diaz. "I'm too busy for this interview I'm doing now."
And while that might sound like just another convenient excuse, once you spend some time in his gym you realize there's at least a little bit of truth to it.
Consider that on his final Saturday before the fight, five hours after he came strolling in the back door of the gym, Diaz is the only one now still on the mats. His friends and training partners are all gone or else waiting around for him to finish so they can finally get a bite to eat. Diaz is still here. He is in no great hurry to leave.
"This is my life," he says once the workout finally winds down. "It's everything I do, train eight-hour days every day. I train hard. This is...yeah, this is my life."
That, he says, is the source of his ill feelings toward Noons. Losing a fight that way, because of cuts, is not something he can just live with. A knockout loss would be easier. At least it would be a clear-cut defeat. But the stoppage on cuts, it robbed him of his chance to find out how the fight would have ended. Noons' subsequent efforts to avoid a rematch, in Diaz's eyes, only made it worse.
"The thing is, I'm not mad," Diaz says. "I never was. I was only mad that he was running and not going to fight me. That makes me angry. Like, you little b-tch. You're running around saying all this? I mean, do that all you want, but take the fight when they offer it. But now he's going to take the fight, so hey, I love that guy now."
It's been a long day of work. Now Diaz is finished, out of the shower, and pulling on his clothes in the locker room. All he really wants, he says, is a fair chance. He wants an opportunity to see the fight played out to its ultimate end, with no interference from doctors or promoters or referees.
Is that so much to ask, he wonders. Can't it just be that simple?
"Just let me take my a--whipping, if that's what it's going to be," he says. "You know? I can handle that. I just want a chance to go in there and see."
Full speed ahead. The only direction he knows.