KANSAS CITY, Mo. -- The regular season begins for the Kansas City Chiefs in 12 days, so they can hear the clock ticking when it comes to the availability of two of their most important players.

Running back Jamaal Charles and linebacker Tamba Hali both recently rejoined the Chiefs at practice after knee surgery; Charles had his in October and Hali's took place after the end of last season. But neither has played in a preseason game. Neither is likely to get into the final exhibition game on Thursday night against the Green Bay Packers at Arrowhead Stadium.

Jamaal Charles' rehab from surgery to repair a torn ACL is going slower than expected. AP Photo/Orlin Wagner

So it’s not just a question of their availability, but also of their effectiveness on Sept. 11, when the real season starts for the Chiefs with a game against the San Diego Chargers at Arrowhead.

“Tamba is a little further along than what Jamaal is right now," coach Andy Reid said. “But both of them are making progress.

“It looks like every day they’re getting a little bit better. They’re moving around pretty good. They’re getting a lot of work, which is important, and they’re pushing themselves. We’ve kind of eased them to this point here and we’ll keep giving them more as we go. Both of them, you don’t have to worry about the work ethic. It’s just a matter of knocking some of the rust off.’’

But both players are behind schedule. The Chiefs said during the offseason that barring a setback, Charles would be ready to participate when training camp started.

There was no setback, but Charles wasn’t ready for the start of camp. He hasn’t regained the role -- full-time featured back -- he had before last season’s torn ACL.

Charles was back and a playing full time by this point of his return from his previous ACL tear, in 2012. But he was four years younger then.

“I’m happy where I’m at,’’ Charles said. “Every time is always different than the first time. I can’t treat it like when I had the first ACL. I’ve got to treat it different.

“The first time I tore it the second game [of the season]. This time I tore it the fifth game. So it’s totally different. The doctor told me when I had [this injury], 'Don't do it like you did the first one because it's totally different.' Every knee is different."

In the meantime, Spencer Ware generally gets a lot of the starter’s snaps in practice. Charcandrick West gets some. Sometimes there are a few left for Charles, too.

“For Jamaal, it’s [a matter of] getting trust in the leg,’’ Reid said. “Every day he does a little but more and a little bit more and his cuts are a little bit sharper. It’s just a matter of time and we’re OK there. We’re OK with that.’’

The Chiefs can afford to take the longer view with Charles. They don’t have that luxury with Hali. Their other top pass-rusher, Justin Houston, was placed on the physically unable to perform list, meaning he is out for at least the season’s first six weeks.

They are counting on at least one more strong season from Hali. He may yet provide that, but he is also getting a later start on it than either he or the Chiefs expected.

“I had surgery on this knee a year prior,’’ he said. “It healed two months later and I was up and running. This one took a little while. I just had to be patient and it’s still a process.’’

Hali has played with chronically aching knees for at least the past two seasons. He hasn’t practiced much during the season.

Hali even talked when he signed his new contract in March of becoming a part-time player, perhaps a situational pass-rusher. With Houston out, the Chiefs can’t afford to do that with him now, and he knows it.

"There’s swelling, there’s pain," Hali said. "That’s part of it. There’s going to be pain in my knee. I can only work through it and get to the passer."