KANSAS CITY, Mo. -- Holdout running back Larry Johnson agreed to a six-year contract extension and joined the Kansas City Chiefs for practice Tuesday, surprising teammates who broke into scattered cheers when he jogged unannounced onto the field.

"Lar-ry! Lar-ry," many players chanted. They had already been practicing for about 45 minutes when No. 27 suddenly appeared in their midst and began running plays.

Johnson, 27, set the NFL record with 416 carries last year while rushing for 1,789 yards, snapping the team record he set the year before. The NFL Network's Adam Schefter is reporting the deal is worth $43.2 million, with $19 million guaranteed. It will keep Johnson, who had one year left on his old deal, with the Chiefs through 2012.

After practice, Johnson quickly dressed and left without speaking with reporters. A team spokesman said he would probably hold a news conference Wednesday. Chiefs president and general manager Carl Peterson said a fine of $14,280 per day for missing 25 days of training would be paid, meaning the holdout cost Johnson about $357,000.

But Peterson joked that with his new deal, Johnson would have no difficulty paying up.

"I think there'll be a little left," he said. Peterson said Johnson called him Monday night "and wanted to chat."

"We met privately," he said. "I could see that he very, very much wanted to get on the field. He explained that to me, that he wanted to be out here with his teammates. I don't know if I've ever seen a guy sign his contract that fast. But he wanted to get out here today and get going."

Without Johnson, the Chiefs have struggled offensively while going 0-2 in their first two exhibition games.

"To be very candid, if he was out beyond the third (preseason) game, that's when I start becoming concerned about veterans," Peterson said.

Johnson's unexpected appearance on the practice field sent a bolt of electricity through what had otherwise been a boring, routine workout in the muggy Midwestern heat.

For a moment, quarterback Brodie Croyle didn't know what everyone was hollering about.

"We were actually in the huddle at the time," he said. "I looked over and saw him. It was good to see No. 27 out there."

Peterson said he was taken aback when Johnson immediately jumped into drills, first blocking on a play and then taking a swing pass from Croyle.

"Frankly, I thought he'd be running on the sidelines," Peterson said.

During his holdout, Johnson was working out at a facility in Arizona.

"He is in really good shape. I have been monitoring his progress," Peterson said. "He's been working very hard. I don't think it will take him long to get up to speed. But there's a soreness aspect you've got to go through. He expressed to me last night he knew that and he didn't want to waste any more time sitting out."

Coach Herm Edwards said Johnson would not play in Thursday night's exhibition game against New Orleans but would be fully ready by the season opener Sept. 9 at Houston.

He has about two weeks now (to get ready). We'll see where we're at. We'll see where he's at," Edwards said. "We talked last night. He knows what I expect out of him. He needs to get his legs up underneath him. He'll have enough time for that."

The running game has suffered. Backup Michael Bennett and rookie Kolby Smith have at times looked good during camp. But the Chiefs rushed for only 61 yards in an 11-10 loss last week to Miami even though the Dolphins held out several of their defensive starters.

"Any time a great player like Larry comes in, we're glad to have him," said cornerback Patrick Surtain. "The guy the past couple of years has been the best back in the league. He certainly deserved what he got. Now he can concentrate on what he does best, run the football."

Guard Brian Waters said he would be curious to see what kind of physical shape Johnson is in.

"To be honest with you, if you're asking for a lot of bread, it would be the craziest thing in the world to not be in shape when you come back," Waters said. "I expected him to be in good shape."

Information from The Associated Press was used in this report.