Kansas City, Mo. ? While most eyes are focused on the quarterback competition inside Arrowhead Stadium on Thursday night, there’ll be drama aplenty at fullback.

It could be, in fact, one of the most important games in Boomer Grigsby’s young life. Drafted in 2005 as a linebacker, the husky, high-energy college trampoline champion was asked last spring to convert to fullback.

With the gusto that has made him one of the most popular players on the team, he jumped into the project full-bore, promising to give it everything he’s got.

But nagging injuries have dogged him much of the summer, and roster cutdowns draw near.

Thursday night’s game against New Orleans will be his first and possibly best chance to show how much progress he has made.

At least one important person will be pulling for him.

“I hope he plays well. I really do,” said head coach Herm Edwards. “He’s done everything we’ve asked him to do. Now he has to go on the field and prove he can play that position.”

Grigsby knows he’s not competing to be the starter. That job belongs to Kris Wilson. But Boomer could be a backup. And he will have the support of a lot of admiring teammates as well as his head coach.

“I’ve seen what Boomer can do in that job. I think if they’ll give him a chance, he can play fullback in this league,” said Brian Waters, who knows a thing or two about switching positions.

Waters came into the league as an undrafted free agent tight end in Dallas, drifted to Kansas City as a center and then was asked to try his luck at guard. Now, as a three-time Pro Bowler, he admires the way Grigsby is attacking a similar challenge.

“Boomer’s had a hard time because he hasn’t been able to get (much practice time). But he has what it takes to be an effective fullback,” he said.

Nobody looks more like a fullback than squat, heavily muscled Grigsby. At 5-foot-11, 250 pounds, he would seem to be the prototype. At the same time, he knows he’s not likely to ever be a great ball carrier – but the Chiefs have never asked for much offense out of the position. Mostly, he’ll be expected to block for Larry Johnson, assuming the two-time Pro Bowl running back ever ends his contract holdout and rejoins the team.

“You’ve got to know your role,” Grigsby said. “I already know my role. I’m trying to compete to play as much fullback as I can, in whatever way they want me to, in whatever way I can help this team.

“I mean, it’s no mystery that they’re not bringing me over here to put the ball in my hands. There is no Heisman Trophy in my past. There are no rushes in my past. They’re putting me there to try to bring some attitude, some stomp, and try to clear the way for the great backs that we’ve got.”

If not for the injuries that began nagging at him the second week of training camp, Grigsby would no doubt be brimming with his customary swagger.

“I’m only 5-11, and that gives me good leverage for the blocking,” he said. “I feel like it’s going great. Every day I try to learn something a little different.”

He’s learned that the art of blocking demands a lot more than a fireplug physique and a taste for violence.

“The whole attitude of running into anybody, that’s never been a problem for me,” he said. “But there’s a lot more to it than that. Sometimes it takes a little more control. There are a lot of times I’ll go up and just smack somebody, and there are a lot of times I’ll just get waylaid because I’m so aggressive. I probably need to be in a little more control in certain situations.”

Even as a fullback, he never considered himself the hittee.

“I look at it, I’m going from the hitter to the hitter,” he said. “In fact, I feel like at fullback, it’s a lot easier to be the hitter because I’m in a three-point stance. I’m already coming out low. I know where the play’s going. So it should be my play each time.”

Whether on offense or defense, he has the same attitude toward contract.

“I love it,” he said with a big grin.

“You can be out there on the practice field in the morning feeling kind of down, trying to focus, trying to get through the day, trying to have a positive outlook. But then you hit helmet-to-helmet with one of the big guys, and that’s the best espresso a man can buy.”