SAN DIEGO -- In the ebb and flow of an NFL season, the San Diego Chargers just ran out of enough healthy bodies against their more rested AFC West rivals, the Kansas City Chiefs.

By the time the officials blew the final whistle on San Diego's first loss in six games, a 23-20 setback on Sunday, the Chargers walked off the field without the team's top two cornerbacks in Brandon Flowers and Jason Verrett, and three energetic, playmaking linebackers in Manti Te'o, Jeremiah Attaochu and Melvin Ingram.

The Chargers finally succumbed to the battle of attrition, and now have only four days to get ready to face the class of the AFC West, the Denver Broncos, on Thursday.

Verrett was inactive for a second game this season, this time because of lingering issues with his surgically repaired shoulder. Flowers suffered a concussion on a big-time collision with former Kansas City teammate Jamaal Charles.

Flowers surprisingly returned to the field for a few plays, but later went to the locker room for further evaluation and did not return.

Te'o (foot), Attaochu (hamstring) and Melvin Ingram (hip) all bring energy to San Diego's second level of the defense. But without them, the Chargers had to rely more on special teams core players such as linebacker Kavell Conner, Reggie Walker and Andrew Gachkar.

The cumulative effect playing without those players was the Chiefs held the ball for nearly 40 minutes and kept it away from San Diego's most precious asset -- quarterback Philip Rivers.

On offense, the Chargers are on their fourth starting running back. They've cycled through four different players at center.

San Diego (5-2) is one of a handful of teams that legitimately can say it can compete for a Super Bowl. But in order to challenge for the AFC West crown and make another deep playoff run, San Diego has to get its young core players back on the field and healthy.

"It's been a tough year with injuries," linebacker Jarret Johnson said. "We've had a lot of guys go down. And it's been pretty amazing to see the type of resilience from the guys that are stepping in.

"Guys are playing different positions. Reggie Walker has played every position in the linebacker room, plus rushed. And there's a ton of situations like that. So the fact that we've had injuries, and continue to have injuries, this team has showed it can weather the storm.

"And with a quarterback like ours, you're always going to have a chance."

But in order for Rivers to perform his wizardry, he has to have the ball. And the Chargers did not have enough possessions against Kansas City.

Rivers, of course, blames himself. The Chargers converted just 3 of 10 third downs and only ran three plays in the third quarter.

"Obviously, our defense was out there tired and fighting like crazy," Rivers said. "And I know they wanted to get off the field in that third quarter, but we've got to help them out."

The Chargers now turn their attention to the Broncos in an important divisional matchup. Last season, San Diego won in Denver on Thursday night, and held the Broncos' potent offense to an average of 24 points in three games. Although battered, the Chargers will be confident heading into Denver.

"It would be nice to be able to have two-and-a-half weeks with all we have going on," Rivers said. "But, mentally, it will be good for us, because we can't sulk and feel sorry about this game.

"And we really shouldn't. … We know what this thing is. This is a 16-week deal you sign up for. And we're here through seven of them, and we're in an OK spot. We've just got to keep going."