Writers aren’t supposed to root for athletes they cover. We are supposed to be totally impartial, and totally objective, so our coverage is as honest as can be.

But a fightwriter has to be excused if at least a sliver of their objectivity is compromised when they come across humble, self deprecating, genial hitter like David Diaz. Especially when we find out that the 32-year-old Chicago resident, a pro since  November 1996 after a stint in the ‘96 Olympics, drives around in a 1991 Honda, with no air conditioning.

Diaz, who gloves up with Manny Pacquiao on June 28, in Las Vegas, spoke on a Tuesday conference call to hype the match with the Filipino icon, who is attempting to snag a title in his fourth weight class. Diaz won the 135 pound interim title from Jose Armondo Santa Cruz in 2006, and he secured the official bauble when he downed Erik Morales last summer.

But his elevated status in the sport took a long time to come to fruition, and he very nearly chucked boxing, back in 2000, after reaching a state of burnout. His wife Tanya, though, convinced him to give it another go, and he re-entered the ring in the fall of 2002 reinvigorated. And win or lose come June 28, we can presume that one of the first purchases Diaz makes post-fight will be a new car, or at least, a respectable used model, with air conditioning.

Diaz’ humor was on display during the call, when I asked him if the no AC Honda quip he made was in jest, or for real.

Diaz said he was not joking. “Why, do you want to buy it?” he said, to laughter.

The boxer, who turned 32 on June 7, got the call off to a lighthearted start when he talked about his rigorous training regimen for the match, which will be Pacquiao’s first at the 135 class.

“I just started training last week,” Diaz said, “and I’m getting ready to finish off.”

It is clear that Diaz hasn’t in fact, been shirking in his training. It is also clear he has a high regard for Pacquaio’s immense technical skills, which have been refined under Freddie Roach’s tutelage. Diaz understands that his best shot to retain his title is to outwork the Filipino, and he told callers that he hopes to do some of his best work in those tiny pockets of time when Pacquiao isn’t busy.

Diaz’ trainer Jim Strickland went out on a limb, saying that he thinks the June 28 tussle will be “one of the best fights of the decade,” and I will go out on my own, and say that I think it will be a fight of the year candidate at least. Strickland has seen Diaz work his tail off in camp, and knows that it will take a state of total unconsciousness for the Chicagoan to quit.

Part of Diaz’ charm is his lack of ego. He told callers that he never expected himself to be enjoying such a prominent role in the sport. His lack of ego was on display back in 1996, after the Games ended, and he told himself that he’d try the pro game if a promoter or manager called, but if not, he’d go back to school, or become a regular working stiff. “I would have a nine to fiver or a five to fiver,” he said.

Diaz is a “five to fiver” in the ring, making up for what he lacks in polish with an uncompromising will to press forward. I believe he’s going to press Pacquiao to the point where the newly polished Manny may well revert back to the old whirling dervish form, and fans will be treated to some scintillating back and forth trades in Vegas and on PPV.

The boxer conceded he is his own worst critic, so there are those that speculate if perhaps he might harbor some self doubt, and ponder if Pacman might be too much for him. Diaz allowed that he sometimes wonders if he’s living “in a dream, fighting one of the most dangerous guys in boxing, if not the top pound for pound fighter.” At the end of the call, he predicted he’d retain his belt, but before that he stated “God only knows what’s gonna happen” on June 28, so clearly, there is a dialogue going on in his head concerning his chances and skills.

The one common opponent the two principals share is Erik Morales. Pacquiao lost a UD to Morales in 2005, avenged that with a TKO10 win in January 2006, and finished the job in November 2006 (TKO3). Meanwhile, Diaz took a UD10 from Morales in Illinois last August. There are those that think Morales, coming in to the bout having lost three straight, won the tiff.  Diaz has watched some tape of Pacquaio against Juan Manuel Marquez from March, and the first Pacman scrap with Morales. He said he saw some deficiencies exposed but neither he nor Strickland would delve deeply into those. Both the fighter and the trainer are hoping that their man has the cardio edge, that perhaps Pacman is looking past Diaz to a megamatch with a Hatton or De La Hoya.

Diaz knows that Mexicans and Mexican-Americans have their fingers crossed that he will be the one to break Pacman’s dominant hold over Mexican fighters. Diaz has been drawing strength from well wishes who approach him, and wish him luck in downing the Manny the Mexi-Killer.

Hey, if Diaz summons some of the ire that he aims at that “AC free” ’91 Honda, as he sits baking in traffic, and directs it at Pacquiao, he could throw cold water on Pacquiao’s lightweight debut, and engineer the upset of the year.