With Ryan Mathews likely sidelined again, the Chargers will rely on Ronnie Brown to head up the run game. (AP Images)

Titans at Chargers -- Week 2

Where: Qualcomm Stadium, San Diego (outdoors, grass)

When: Sunday, 4:25 p.m. ET (CBS)

Spread: Chargers by 6

Forecast: Clear skies with a light southwest breeze; projected kickoff temperature: low-80s.

Records: Chargers (Overall: 1-0, AFC West: 1-0); Titans (Overall: 0-1, AFC South: 0-0)

Past results: Two most recent meetings -- Oct. 31, 2010: Chargers 33, Titans 25; Jan. 13, 2008 (AFC Wild Card): Chargers 17, Titans 6. Series record: Chargers hold a 25-16-1 edge. The Titans have a 1-3 postseason advantage. San Diego has won eight straight games between the two and are 16-5-1 in the series as the home team.

What matters: The Chargers running game needs to get in gear. The backs struggled throughout preseason and only rushed for 32 yards on 20 attempts on Monday night against the Raiders. The Patriots rushed for 162 yards vs. the Titans last week. Good yardage on first-down runs consistently allowed Tom Brady to move the chains with short, safe passes. QB Philip Rivers should be able to do the same if the Chargers running game is moderately productive.

Who matters: RB Ryan Mathews (clavicle) is listed as questionable but is closer to doubtful. Mathews hasn't fully participated in practice since he broke his right clavicle in the preseason opener on August 9. If Mathews doesn't start, the Chargers will need more production from RB Ronnie Brown, who only rushed for 5 yards on five carries against the Raiders. The Chargers defense will have to keep Titans RB Chris Johnson in check. Johnson had a career low 4-yard performance last week. Rivers threw a career-high 20 interceptions in 2011. He got off to a good start this season with no interceptions in the season opener. If Rivers continues to be smart with the ball, the Chargers should dominate.

Key matchups: Chargers LT Michael Harris (undrafted, UCLA) vs. Titans DE Kamerion Wimbley. Harris made it through his first game without giving up a sack, but for the most part Harris faced off against Raiders DE Matt Shaughnessy, who is known for his rushing defense, not rushing the QB. Wimbley played for the Raiders last year and sacked Rivers four times in Week 10, and he got a sack on Brady once last week.

Injuries of note: Chargers LT Jared Gaither (back spasms) and CB Shareece Wright (right ankle sprain) are out. Mathews (clavicle) and TE Antonio Gates (ribs) are questionable. Gates is more likely to play than Mathews. CB Quentin Jammer underwent surgery on his right thumb on Tuesday but is listed as probable. Titans middle linebacker Colin McCarthy (ankle) and RB Javon Ringer are out. WR Nate Washington (calf) missed practice every day this week, but he may play.

Inside stuff: With CB Shareece Wright out, the Chargers will have only three CBs active on Sunday. The safeties are prepared to play nickelback in case an injury were to occur to another CB. “Nickel is a position that could be played by a safety or a corner,” SS Darrell Stuckey said. “As a DB, if you have a position that is interchangeable, we are all expected to know it.”

Note: It is possible CB Greg Gatson could be activated off the practice squad prior to the game.

Connections: Chargers wide receivers coach Charlie Joiner was an Oiler (now Titans) from 1969-72. He was drafted by the franchise in the fourth round in 1969. Titans DE Dave Ball (reserved-injured) went to UCLA and was a fourth-round pick of the Charges in 2004. Ball spent parts of the 2004-05 seasons in San Diego. Titans offensive lineman Eugene Amano (reserved injured) is a San Diego native who attended Rancho Bernardo High School.

Stat you should know: Chris Johnson rushed for more yards (5,645) than any player through his first four seasons (2008-11). He rushed for a career low 1,047 yards in 2011 and was limited to 4 yards on 11 carries against the Patriots last Sunday. That adds up to 13 inches per carry. It brought his league-leading career average down from 4.8 to 4.7 yards per carry.

Record watch: Gates needs just three catches to become the fifth tight end and 59th player in NFL history with 600 career catches. General manager A.J. Smith has 92 wins as San Diego’s GM and needs just one more to become the winningest GM in Chargers franchise history.  

Looking ahead: If the Chargers win, it will mark their first 2-0 start under coach Norv Turner (2007-present). San Diego started 2-0 in 2006 under coach Marty Schottenheimer and finished the season 14-2, the best regular season in franchise history. The Chargers will stay home to host the Falcons next Sunday in what should be a good game.

Prediction: Chargers 27, Titans 16

Follow the Chargers and Dan McLellan on Twitter @CBSChargers and @sandiegosports.