How the Chargers and 49ers match up in Week 4

San Francisco (1-2) at Chargers (1-2)

When Chargers have the ball

Without attracting a ton of attention, Philip Rivers is off to an impressive start, averaging 302 yards passing with the fifth-best quarterback rating in the NFL. He has eight touchdowns to one interception, stats that certainly could improve Sunday in the absence of 49ers cornerback Richard Sherman, who will miss the game because of a calf injury. The 49ers have struggled defensively in large part because of the lack of a pass rush. This would seem to be inviting major problems when facing a quarterback seemingly headed for the Hall of Fame. Only Drew Brees and Aaron Rodgers have more attempts with fewer interceptions this season. The Chargers also are averaging 5.5 yards per rush, a figure topped only by Dallas and San Francisco. On first down, the Chargers are gaining more than 6.5 yards with each run. But led by linemen Solomon Thomas, DeForest Buckner and Arik Armstead, the 49ers are the 10th-best defense in the league against the rush. Thomas, Buckner and Armstead were first-round draft picks out of the Pac-12. The Chargers again will be without right tackle Joe Barksdale (knee), but his replacement, Sam Tevi, has been able to obscure Barksdale’s absence for nearly three full games.

When 49ers have the ball

San Francisco’s season took a sharp turn last week when quarterback Jimmy Garoppolo was lost for the season because of a knee injury. Now, it’s up to second-year pro C.J. Beathard to steer the offense back on course. The Chargers have seen him only briefly in each of the last two preseasons, football in August hardly a reliable barometer for what could happen when the real games begin. They will attempt to make matters difficult for Beathard, but have struggled sustaining a pass rush with Joey Bosa (foot) out. This should be the final game missed by defensive tackle Corey Liuget, who’s scheduled to return next week after serving a suspension for using performance-enhancing drugs. It shouldn’t matter who’s handing off the ball for the 49ers, considering they’ve averaged 152.7 yards on the ground, second-best in the league. Through three weeks, Matt Breida was leading the NFL with a per-rush average of 8.6 yards. His 274 rushing yards were tied with Dallas’ Ezekiel Elliott for second best in the league. Breida is in his second season out of Georgia Southern. The Chargers have been a bottom-10 team against the run.

When they kick

For the first time this season, Caleb Sturgis missed an extra point last week. That was hardly the difference in a 35-23 loss to the Rams. but every miss by a Chargers kicker is notable because of the potential doom it could foreshadow. To this point, Sturgis hasn’t figured prominently in the outcome of a game. That’s something that could change. San Francisco’s Robbie Gould also missed an extra point last week, but he has made all eight of his field goal attempts, the longest being 45 yards.

Jeff Miller’s prediction

Before the Garoppolo injury, the Chargers would have been favored at home. Now, they’re favored by double digits. This is a game the Chargers should win, the most dangerous X-factor being the 49ers’ young quarterback and the way unproven passers can sometimes suddenly emerge in this league. It seems unlikely, even with a stout running game, that the 49ers will be able to keep pace with Rivers and a Chargers offense with plenty of options.

CHARGERS 42, 49ERS 20