KANSAS CITY, Mo. (AP) — When he planted his right foot and his knee buckled beneath him, the first thing that went through Jamaal Charles’ mind was that it couldn’t possibly be something serious.

Not a torn ligament. Not again.

Then, the star running back for the Kansas City Chiefs from Port Arthur was hit with reality. For the second time in five seasons, one of the most dynamic players in the NFL had torn the ACL in his knee. He was done for the year, and faced the prospect of another round of grueling rehabilitation.

Just as his team’s season was spiraling out of control.

“Even then, I was just chill,” Charles said. “I just wanted to get the surgery done and get back on my feet again. I want to be ready for the start of next season. I want to play.”

The Chiefs do not allow injured players to speak to reporters at their facility, but Charles agreed to discuss his surgery, recovery and the road back with The Associated Press.

The play that ruined his season was about as innocuous as they come.

After taking a handoff from Alex Smith in Week 5 against Chicago, the four-time Pro Bowler darted forward. He planted his right foot and tried to go left, where a hole was opening up, and his right knee seemed to collapse. He fell face-first into the turf at Arrowhead Stadium, which was suddenly as quiet as a funeral parlor.

“It wasn’t something I was even thinking about,” Charles said of an ACL injury. “I was just thinking about getting an MRI and seeing if it was a sprain or something.”

The NFL is a cruel sport, though. So while Charles had taken countless hits since tearing the ACL in his left knee at Detroit in 2011, and almost every time popped right back up, it was a play that didn’t even involve contact that took him down.

And robbed Charles of another year of his prime.

After recovering from his first knee injury, he came back to run for a career-best 1,509 yards. The following year, he ran for a career-high 12 touchdowns. And last season, he went over 1,000 yards rushing for the third straight season despite some nagging bumps and bruises.

This year was off to a steady start, too. Until the game against Chicago.

There are differences between the first knee injury and this one, Charles said. The rehab from his first made both legs stronger, and that has given him a better base to begin his recovery this time. He is also right-handed, so his right leg is naturally a bit stronger.

But nothing is more important than his outlook. He was emotionally distraught when he got hurt in the second game of the 2011 season, nervous and uncertain about the future. But he’s gone through this process once, and that has left him in better spirits.

“It’s easier,” he explained, “just because I know what I know.”

That doesn’t mean this recovery isn’t without challenges.

There were difficult days after he was operated on by Dr. James Andrews, and every workout is painful. Then there are those who argue his injury was a blessing for a Chiefs team that lost five of its first six games. Without Charles on the field, coach Andy Reid has become more creative on offense and they have won six straight after Sunday’s win in Oakland.

“That’s OK,” Charles said. “I’m not worrying about what anybody says. What they were doing when I was there, they could still be doing it.”

Besides, Charles said, “it ain’t me. It’s Coach Reid’s system. I’m just a part of it.”

Indeed, Charcandrick West and Spencer Ware have become fantasy football must-haves while they fill in for Charles, and both journeymen credit him for helping them learn the ropes.

“I’m happy for their success,” Charles said. “I knew if we got on the same page, we’d be winning. I feel like they’re all clicking on the same page.”

But it’s difficult to watch the sudden success from afar. Charles basically spends his time rehabbing his knee, playing video games — “Destiny” is his title du jour — and spending time with his family, all while wishing he could contribute on the field.

Charles turns 30 next season, ancient for running backs in the modern NFL. But his shiftiness means he rarely takes shots squarely, so he doesn’t have the wear and tear of many others at his position. And the fact he’s missed most of two seasons because of knee injuries means, assuming he fully recovers from this one, he could have a few good years left.

In other words, Charles intends to earn the $5.75 million in salary and bonuses he is due next season, part of a contract extension signed with Kansas City prior to last season.

“That’s the goal,” he said. I had 11 (games) left in the season when I did it, so it’s a lot of time to come back from it. The way I’m moving, I’ll be back before the season starts. I want to be back. I want to play. I want to be out there again.”