Jamaal Charles became the NFL's leading rusher and proved he's back last week against New Orleans. (AP)

Chargers at Chiefs -- Week 4

Where: Arrowhead Stadium, Kansas City, Mo. (natural grass, outdoors)

When: Sunday, 1 p.m. ET (CBS)

Spread: Chargers by 1

Forecast: Mostly sunny, 70s

Records: Chiefs (Overall: 1-2, AFC West: 0-0); Chargers (Overall: 2-1, AFC West 1-0)

Past results: Two most recent meetings -- Oct. 31, 2011: Chiefs 23, Chargers 20; Sept. 25, 2011: Chargers 20, Chiefs 17. Series record: Chiefs lead 52-50-1.

What matters: The Chiefs rallied from an 18-point deficit in New Orleans to pull off the greatest comeback in franchise history. Now for a dose of reality: That comeback came against a winless team whose opponents are winless when they're not playing the Saints. Whether the win came against a battered team or not, the Chiefs had a lot of positives to spin forward. The defense was so dominant in the fourth quarter and overtime that Drew Brees and the Saints went backwards 16 yards. Jamaal Charles proved his knee is just fine, running for 233 yards on a career-high 33 carries. And the Chiefs' offense after halftime looked like the 2010 version that made the playoffs and led the league in rushing. (They are again leading the league in rushing). By the Falcons knocking off the Chargers and the Broncos losing their second straight, the Chiefs have a chance to play for a first-place tie in the AFC West, which would begin to erase an awful two-week stretch to start the season. 

Who matters: Matt Cassel. Cassel made several clutch throws late in the game against the Saints to keep the comeback alive. But for most of the game, Cassel was not good. He often threw too high, putting his receivers in vulnerable positions. The Saints have the worst rushing defense in the NFL, and the Chargers rank sixth, allowing 67.3 yards per game. So it's not going to be as easy to run the ball and it's likely the Chargers' focus will be to stop the Kansas City run. Cassel will need to play better to move the ball against San Diego's defense. He also needs to do a better job of getting rid of the ball -- he's taken 11 sacks in three games. 

Key matchups: Chiefs' OLBs Justin Houston and Tamba Hali vs. Chargers' offensive tackles. Houston was a game-changer with three sacks and a safety against the Saints. He has 9.5 sacks in his past eight games. Hali does not have a sack this season, but he will either be going against undrafted rookie free agent LT Michael Harris or former Chief Jared Gaither, who might play for the first time this season. TE Antonio Gates vs. S Eric Berry. Because of injuries, Berry and Gates have only gone against each other once, Berry's NFL debut in the 2010 opener. Gates got the best of Berry that day with five catches for 76 yards and a touchdown. Gates has 12 career touchdowns in 14 games against the Chiefs, more TDs than he has against any other team. 

Injuries of note: Injuries continue to be a major problem for the Chiefs. Two starters appeared on the injury report for the first time this week in WR Dwayne Bowe (groin) and DE Glenn Dorsey (calf). They were limited Thursday but expect them to play. The Chiefs will likely be without RB Peyton Hillis (ankle), TE Kevin Boss (concussion), WR Dexter McCluster (elbow), NT Anthony Toribio (ankle) and S Kendrick Lewis (shoulder). C Rodney Hudson was placed on injured reserve this week and is out for the year. 

Inside stuff: Charles ran for more than 100 yards for the first time last week since the 2010 season. In 2010, the Chiefs were 6-1 when Charles ran for at least 90 yards. 

Connections: Gaither played 10 games for Kansas City last year until he was cut. He immediately signed with the Chargers, who started him for the final five games. RB Jackie Battle played his first five seasons in Kansas City and has 124 rushing yards and two touchdowns to lead the Chargers in rushing. LB Demorrio Williams spent the past four seasons in Kansas City and signed with San Diego as a reserve in the offseason. San Diego FB Le'Ron McClain spent 2011 with the Chiefs. Kansas City backup LB Brandon Siler played his first four seasons in San Diego before signing with the Chiefs prior to the 2011 season. 

Stat you should know: The turnover battle could play a big part. The Chiefs have an NFL-worst minus-8 turnover margin. San Diego lost the turnover battle for the first time last week, 4-1. RB Ryan Mathews fumbled at the Atlanta 5-yard line, and QB Philip Rivers threw two interceptions. 

Looking ahead: The Chiefs welcome Baltimore to Arrowhead next Sunday. On paper, most would probably heavily favor the 3-1 Ravens. But Baltimore has not been a great road team the past two years, going 4-6 (playoffs included) and are 0-1 this year. Since the Ravens played Thursday, they do have a few extra days to prepare.

Prediction: Chargers 23, Chiefs 20

Follow Chiefs reporter C.J. Moore on Twitter @CBSChiefs and @cjmoore4.