The 34-33 defeat Sunday did not, however, severely damage their chances of returning to the postseason after last year's 8-8 struggle.
Baltimore (7-5) stands tied for second place in the AFC North with Cleveland and Pittsburgh behind Cincinnati (8-3-1), which still has two games left against the Steelers.
The Chargers are the only team in the wild-card hunt at 8-4, but they've got a tough schedule in December: New England, Denver, San Francisco and Kansas City.
So the Ravens have reason to be optimistic, even after blowing a 10-point advantage in the final six minutes of a rare home defeat.
''We had a real opportunity to capitalize if we'd have held that lead. It would have put ourselves in good position,'' coach John Harbaugh said Monday. ''But we find ourselves in good position anyway, the way it's shaking out. It's going to be very competitive (and) down to the wire to make the playoffs, to win the division, and we are in the thick of it.''
Baltimore travels to Miami on Sunday. After that, the Ravens host Jacksonville, travel to Houston and wrap up the regular season at home against Cleveland.
''We have a huge game down in Miami this week,'' Harbaugh said. ''There will a lot on the line and they'll be ready and they're good. We'll have a great opportunity to make a move.''
For Baltimore to reach the postseason, its pass defense must improve. Philip Rivers threw for 383 yards and four touchdowns to bring San Diego back and saddle the Ravens with their first home loss in November since 2009.
Baltimore defensive coordinator Dean Pees tried just about everything to stop Rivers, including rotating cornerbacks and calling a variety of blitzes.
Nothing worked. The Chargers converted nine of 11 third-down tries and punted only once.
''We've got to make some plays back there,'' Harbaugh said. ''We had a couple things that were issues as far as assignments. We didn't play the routes a couple times right, gave up a couple big plays. That's really what it boils down to. The other balls were contested balls and contested catches for the most part.''
It wasn't just the secondary. Rivers threw 45 times and was sacked only twice, and on one of them he got back to the line of scrimmage.
''We didn't hit him enough,'' defensive end Chris Canty said. ''He was able to get the ball out on time to his receivers. We take great pride in being able to rush the passer, but we didn't make enough plays up front and help our guys on the back end enough. That hurt us.''
Penalties were a factor, too. The Ravens were flagged a whopping 14 times for 98 yards, with many of the fouls coming at the absolute most inopportune time.
Two of those penalties occurred during the final, decisive drive. A sack of Rivers was wiped out when linebacker Elvis Dumervil was offside, and a pass interference call against Anthony Levine set up Rivers' game-winning, 1-yard touchdown throw with 38 seconds remaining.
''We have a category we call `foolish penalties,''' Harbaugh said. ''We had too many of those unnecessary penalties that you don't gain anything from and cost us. Unfortunately, the penalties that we had, especially on defense, were the ones that gave them a chance to extend those drives.''
After the Ravens went up 30-20, Daryl Smith was called for holding on a third-down incompletion. Rivers threw a touchdown pass on the next snap.
Plays like that made watching the film Monday tough to take.
''We're better than that,'' Harbaugh said. ''We can do better than that, and that was a disappointing part of it.''
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