SAN DIEGO (AP) -The San Diego Chargers found out they're not quite so invincible, after all.

Feeling they were one of the NFL's elite teams, the Chargers went into Kansas City and fell behind 20-3, thanks to three first-quarter turnovers. They rallied to tie the game, but lost 30-27 on a last-second field goal.

While they were flying home, news broke that star outside linebacker Shawne Merriman tested positive for steroids and was facing a four-game suspension.

So they'll be trying to rebound on two fronts when they host the St. Louis Rams on Sunday in a matchup of teams with 4-2 records. The Rams are coming off their bye.

If losing to the division rival Chiefs wasn't bad enough, Merriman's positive drug test adds another off-field issue to a team that's had plenty this season.

Merriman said the positive test stemmed from a tainted supplement. An appeal hearing is expected to be held Nov. 7, meaning he'll play the next two games.

Having Merriman at least for the next two games is good news to a defense that will be missing outside linebacker Shaun Phillips and end Igor Olshanksy due to injuries.

Kansas City ``was one of the teams we should have won against, a divisional game,'' Merriman said. ``We've got to win those. We're not going to be the team we want to unless we do. If we don't win those games now, we're going to find ourselves in the same situation we were last year, where we have to win out just to get into the playoffs and be where we want to be.

``We learned a pretty good lesson.''

Of course, while the Chargers needed to win out last year to get into the playoffs, they didn't come through, missing the postseason for the ninth time in 10 seasons.

Rams coach Scott Linehan doesn't think Merriman's style will be blunted by off his off-field issue.

``I think all people can be quick to judge,'' Linehan said. ``Certainly, it's one of those things that for whatever reason, he's got something he's got to deal with. We played against him last year. I've been following him, especially in the last couple of years, some of these players have been coming out that have been really impact-type players like Merriman, and really admire what they're able to do as players.

``In this case, I think it's one of those things that it's probably just a temporary setback for him, and I'm sure he'll learn from whatever it was and move on.''

The game will feature two of the NFL's highest-rated quarterbacks. St. Louis' Marc Bulger is third in the NFL with a 99.8 rating and San Diego's Philip Rivers is sixth at 96.3.

Rivers, in his first season as starter, will be trying to forget the two turnovers he committed in the first quarter at Kansas City. Running back LaDainian Tomlinson had the other turnover.

``I tried to find the positives out of it,'' Rivers said. ``Obviously the negatives you have to correct. The start was obviously crucial in the outcome. But at the same time, you have that kind of start and crawl back. We tied it up there late. I kind of bounced back and just kept on playing, and our team did that as well.''

Rivers said the Chargers are in a good frame of mind despite the loss.

``You had a tough loss, yeah, you wish you had got it, but you keep going. We are 4-2. There's a lot to be positive about and a lot of things we can still attain.''

Bulger, meanwhile, is adjusting well to Linehan's offense. Bulger has thrown 10 touchdown passes and just one interception, with 1,619 yards. His favorite receiver is Torry Holt, who has 37 catches for 526 yards and seven touchdowns - three in his most recent game.

Bulger had to go through an adjustment period because Linehan's offense is more conservative than the one used by former coach Mike Martz.

``It was frustrating at first, but if it took one or two weeks into the regular season, in the big scheme of things, that's not a long time,'' Bulger said. ``Some offenses take a year or two to learn. We're still early into the season. Everyone is getting more comfortable with it and embracing it.

``I approach every week the same,'' he added. ``If the numbers are good, they're good. If not, they're not. We're 4-2 and that's all that matters to me. Whether my stats keep going good, it doesn't matter.''

A weekend off gave the Rams time to regroup from their toughest loss of the season, a 30-28 defeat to NFC West rival Seattle on Josh Brown's 54-yard field goal as time expired.

The Rams have lived on the edge all season. Their six games have been decided by a touchdown or less, and four came down to the final seconds.

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