St. Louis Rams (4-6) at San Diego Chargers (6-4)

Sunday, 4:05 p.m. ET, at Qualcomm Stadium, San Diego – TV: FOX

*TV announcers: Chris Myers, Ronde Barber, Jennifer Hale

*Keys to the game: With their defense playing lights out over the past month-plus, the Rams made the switch back to veteran QB Shaun Hill last week and the results were immediate in a shocking thumping of the Broncos.

St. Louis is now featuring rookie RB Tre’ Mason, who brings more acceleration to the backfield equation than Benny Cunningham or Zac Stacy. The Rams are content to play the field position game while setting up the occasional vertical shot, and caught Denver napping last week.

Fireworks could be limited on both sides of the ball with Chargers QB Philip Rivers debunking TE Antonio Gates’ assertion that he has been playing through a significant rib injury. What is known is that Rivers has struggled during the Chargers’ 1-3 stretch with shaky line play. That’s a frightening proposition with the Rams dialing up constant pressure across their deep defensive line.

The key for the Chargers — and for Rivers’ health — is to get a strong game out of RB Ryan Matthews, who returned to the lineup last week. The Rams are still allowing 100.8 rushing yards per game, and San Diego must stay out of third-and-longs to sustain drives.

*Matchup to watch – Rams DTs Michael Brocks and Aaron Donald vs. Chargers C Rich Ohrnberger: The Chargers are hoping Ohrnberger can gut it out through back and ankle injuries, but he managed just half of the snaps last week. If he can’t go, rookie OG Chris Watt slides to the middle and becomes responsible for the line calls.

*Player spotlight – Chargers OLB Melvin Ingram: So much for easing back into action after missing nine games due to a hip injury. Ingram played 90 percent of the defensive snaps last week, although he did not apply much pressure on the quarterback.

*Fast facts: After registering just one sack through the first five games, the Rams have 18 over their past five. … The Chargers have converted just seven of 26 third downs over their past two games.

WHO WILL WIN AND WHY

The Chargers have defeated one team with a winning record all season, and have looked very shaky during a 1-3 stretch. The Rams have beaten three winning teams over the past five weeks and coach Jeff Fisher has his young squad playing hard on both sides of the ball.

*Our pick: Rams 20-16