The Chargers will be without leading receiver Keenan Allen for at least a week after the second-year pro suffered a broken collarbone in addition to an ankle injury in San Diego's loss last week to the Denver Broncos.
"My shoulder was hurt during the game, but I wasn't too worried about it more than I was the ankle," Allen told the Associated Press.
Allen has caught 77 passes for 783 yards and four touchdowns this season. As a rookie, the 6-foot-2, 211-pound receiver out of California lead the Chargers with 1,046 receiving yards and eight touchdowns last season.
While the Chargers haven't technically been eliminated from playoff contention, they face a hard road to get there. In fact, that's exactly where they'll have to win to have a shot at a wild-card berth.
If San Diego is able to win in San Francisco on Saturday before traveling to Kansas City, Mo., next week where they'd need to beat the Chiefs at Arrowhead, one of the loudest stadiums in the NFL, they'd still need losses from the Ravens, Steelers or Bengals to reach the postseason.
The easiest path requires Baltimore to lose one of its last two games, at Houston or against Cleveland, since San Diego owns the tiebreaker thanks to its Week 13 win over the Ravens, 34-33.
Otherwise, the Chargers need the Steelers to lose their last two, against the Chiefs and the Bengals, or they could reach the playoffs with two losses from the Bengals, against Denver and at Pittsburgh.
The Broncos clinched the AFC West division title on Sunday with their 22-10 win over the Chargers.
Follow Matt Wilhalme on Twitter @mattwilhalme