Holmes, a three-time Pro Bowler, turns 34 in October and has been out of football since 2005 after suffering what many figured was a career-ending injury. The Chiefs are not planning on him being anything more than a situational back, if he returns to the field at all.
But he created a stir in July with his surprise return and said this week his comeback attempt is going well as he works himself back into game shape.
He's still on the physically unable to perform list while veteran Michael Bennett and rookie Kolby Smith take most of the snaps at running back. But on Tuesday, he was on the practice field in pads, taking handoffs and absorbing hits from assistant coaches using blocking pads.
Afterward, he said he's ready to fill the 27-year-old Johnson's shoes -- at least financially.
"Somebody has to get the money," he said. "Hey, if L.J. wants to leave the money out there, guess I'm going to take it. If he wants to come get it, it's rightfully his to take. He's earned it. But if he chooses not to come back, well, somebody has to take it. Why won't it be me?"
Johnson has been a no-show at camp as he seeks an extension to the seven-year contract he inked in 2003, which he can void down to a five-year deal after the final game of the 2007 season because of playing time incentives.
Both head coach Herm Edwards and Chiefs president Carl Peterson have said Holmes will not be their feature back.
"If he's able to come back, he understands and accepts the fact that he would have a different role than when he was the starter," Edwards said.
Johnson is demanding compensation in the range of $28 million guaranteed, insisting he be paid as much as league MVP LaDainian Tomlinson. Johnson is scheduled to earn $1.7 million this season and is being fined more than $14,000 for every day he misses.
One of the NFL's top runners until his injury, Holmes rushed for a team-record 5,933 yards after signing as an unrestricted free agent in 2001. He scored 27 touchdowns in 2003, then an NFL record.
He's been on the physically unable to perform list since a devastating tackle by San Diego's Shawne Merriman on Oct. 30, 2005, left him with head and neck trauma. After extensive tests, doctors warned of a possibility of further injury, perhaps even paralysis --
a danger that may still lurk.
"This is about perseverance and having a great story to tell," Holmes said. "I think that all the valuable years I've put into my tank, there's a lot in me still."
Some were dubious about Holmes' motives for returning, especially in light of Johnson's holdout.
"'Dubious' is a great word," Holmes said. "But dedication is a little bit more defined in concrete. I mean, we have what's called 'making it rain.' We have the dogfighting, we have so many things that have cast a negative light on the NFL. This is just a great story to show guys that regardless of what situation you're in, you can persevere."
Holmes, who received a clean bill of health from Kansas City's doctors before reporting to camp, last played a full season in 2003. He played in eight games in 2004 before a hip injury and then played in seven games in 2005 before the helmet-to-helmet hit from Merriman.
Holmes said seeing highlights of himself this summer during a football camp made him start thinking about returning to the Chiefs.
"Once I saw myself, the first thing I looked at it was as if I was a fan," he said. "I said, 'Man, I did that? Oh, that's a nice run. Oh, I love that touchdown move right there. I got to do that again.'
"I haven't had any setbacks so far," he added. "The biggest thing with football is taking all the contact and then continuing to run."
Chiefs guard Brian Waters, an eight-year veteran and a good friend of Holmes, said players are keeping an eye on the running back's progress.
"We know just by watching him run, he's still got a lot of his abilities," Waters said. "His quickness is strong. It's going to be a mental thing, for sure, but we'll see. I've seen him come back from serious injuries before and have a great season, so nothing would surprise me coming from that man."