Jimmy Garoppolo presents solid opportunity for Beathard

The devastating injury suffered by Jimmy Garoppolo presents a solid opportunity for C.J. Beathard.

The second-year pro begins his second stint as San Francisco's starting quarterback on Sunday when the reeling 49ers (1-2) visit the Los Angeles Chargers (1-2) at StubHub Center in Carson, Calif.

Garoppolo tore the anterior cruciate ligament in his left knee in last Sunday's defeat to the Kansas City Chiefs. The injury to the franchise quarterback emotionally crushed coaches and players alike and also sparked concern that the 49ers won't be able to compete this season.

Beathard, though, wants to be more than a caretaker. He started five of seven games played last season before Garoppolo became the starter and the transition initially had him feeling anger at coach Kyle Shanahan and the organization.

"That's so far in the past, it's hard to look back to that," said Beathard, who passed for 1,430 yards, four touchdowns, and six interceptions last season. "But I looked at it as an opportunity to grow and learn and get better and just be the best backup that I could be all the way up to this point. And just learn from Jimmy and Kyle and take it all in."

Shanahan told his team it was natural to feel in a down mood after Garoppolo's injury. But the message was also made that feeling sorry too long isn't conducive to winning football games.

"We can't really sit back and mourn and feel bad for ourselves while the Chargers are out there practicing, getting better," said tight end George Kittle, who was a college teammate of Beathard at Iowa. "They don't really care. So we're just going to move forward and we're just going to do what we can with what we got and we're going to win some games."

The 49ers promoted Nick Mullens from the practice squad to be the backup.

Los Angeles certainly needs a victory or otherwise puts itself at risk of falling three games behind Kansas City in the AFC West.

The Chargers are performing well on offense with an average of 27.3 points but the defense is allowing 31 per game, second worst in the NFL. Veteran tight end Antonio Gates says there is plenty of time for the team to put things together.

"Nobody has won the Super Bowl in the first four weeks -- not that I can remember," Gates told reporters. "So this is something that we can build on, and I understand every game is something you have to take advantage of and embrace the opportunity."

Los Angeles quarterback Philip Rivers is off to a good start with 906 yards, eight touchdowns, and one interception. He is pleased with an attack averaging 415.3 yards per game.

"The best offenses we've had in my time here have been very balanced -- not to say that we haven't had big days throwing the ball and some days running it -- but very balanced," Rivers said. "That's what it feels like right now. We're really complementing the run and the pass and we're getting a lot of first downs."

The defense has been hurt by the season-long absence of defensive end Joey Bosa (foot), who has 23 sacks in 28 career games.

The 49ers also will be missing a key player in cornerback Richard Sherman, who will miss multiple weeks with a calf injury.

The status of San Francisco running back Matt Breida (knee) won't be firmed up until Sunday. He is listed as questionable but Shanahan said the decision on his availability will be made prior to the game.

Breida has 274 rushing yards and is tied for league lead with Ezekiel Elliott of the Dallas Cowboys.