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Jim Harbaugh was hoping for a little "Luck" against his old college quarterback last week. Instead he got a giant distraction from his troubled All-Pro linebacker.

And now the reigning NFC champion San Francisco 49ers head to America's heartland underwater as they prepare to face off with the St. Louis Rams on Thursday night.

Andrew Luck's return to the Bay Area was a smashing success, much to the chagrin of his college mentor Harbaugh. The ex-Stanford star ran for a touchdown while putting together an efficient performance under center, as the Indianapolis Colts clamped down defensively on their way to an impressive 27-7 victory over the 49ers at Candlestick Park.

Luck completed 18-of-27 passes for 164 yards and did not turn the ball over in outplaying young counterpart Colin Kaepernick, while getting a big assist from a Colts defense that held the struggling 49ers offense to 254 total yards and kept Kaepernick firmly under wraps.

One week after committing four turnovers in a 29-3 loss at Seattle, Kaepernick managed just 150 yards on 13-of-27 passing while being intercepted once and losing a fumble.

"We have to be better," Kaepernick said. "I have to be better. I have to be able to make throws down the field."

Frank Gore finished with 82 rushing yards on 11 attempts for San Francisco (1-2), which fell under .500 for the first time in the three-year tenure of Harbaugh.

And Harbaugh was a loser on two fronts in Week 3, as his misstep on the football field paled in comparison to his handling of Aldon Smith, who was taken into custody the Friday morning before the game for suspicion of DUI after running his truck into a tree at 7 a.m.

Smith blew a .15 on his breathalyzer test -- almost double the legal limit in California -- and marijuana also was found in the vehicle. It was the second time Smith had been arrested on DUI chargers over the last 20 months, a time frame which includes an incident in which Smith was stabbed at a house party.

So with Smith's life clearly spiraling out of control, he was bailed out and back on the practice field with his team hours after the incident, a black mark on what has been quite a honeymoon for Harbaugh in the Bay Area.

Common sense still hadn't taken hold by Sunday and Smith played in all 67 of San Francisco's defensive snaps against the Colts with Harbaugh and the 49ers hiding behind the collective bargaining agreement, which to be fair did take a suspension off the table.

The CBA says only the league can suspend players for substance-abuse issues, something that will assuredly happen once the case itself is adjudicated. That said, Harbaugh could have easily taken a stand as both a football coach and a human being by simple deactivating Smith.

After the game the team announced he would be taking an indefinite leave of absence to seek help for a substance-abuse problem and by Monday Smith was on the reserve/non-football injury list.

"I am taking a leave of absence to address my health," Smith said in a statement on Monday. "I am sorry that I have affected my team, my family and the organization. I will do everything in my power to handle this situation the best way possible. I appreciate the support of the 49ers and our fans."

The Rams have their own concerns and they usually start with Cowboys running back DeMarco Murray, a mild-mannered Clark Kent-type against the rest of the league before slipping into a phone booth and transforming to Superman against St. Louis.

Murray exploded for 175 yards and a touchdown on 26 carries, while Tony Romo threw for three scores, as Dallas pounded St. Louis, 31-7, last Sunday in Week 3 action.

In his previous effort against the Rams back on Oct. 23, 2011 in Arlington, a then-rookie Murray filled in for an injured Felix Jones and ripped off a franchise-record 253 yards on the ground, breaking Emmitt Smith's mark of 237 yards along with the single-game Dallas freshman record of 206 yards held by Tony Dorsett.

"We didn't run it, we didn't stop the run, we didn't throw it, we didn't stop the passing game." Rams coach Jeff Fisher said. "They are a good football team, I didn't see this coming. This is a defining moment for us right now. We've got to get past this and get ready for the 49ers."

Sam Bradford ended up 29-of-48 for 240 yards passing and a TD pass to Austin Pettis for the Rams (1-2), who have dropped two in a row overall.

"In the first half, we just never got anything going, played behind the chains all day," Bradford said. "Just a very poor performance on our part."

In fact St. Louis performed so poorly it had a closed door meeting after the contest in an effort to stave off any dissension.

"This is the NFL. I hate to state the obvious, I'm not trying to. No team is beyond getting beat any given day, and beat badly," defensive end Chris Long said. "I don't think we didn't prepare well. Guys just didn't execute and perform.

"We are going to stick together. Those things are between coaches and players. We have to stick together. Nobody is going to come in here and save the day. It is on us to change things."

The Rams and 49ers have met twice annually since 1950, and Thursday night's contest will be the 127th regular-season game between the teams. The Rams hold a slight lead in the all-time series, 62-61-3.

WHAT TO WATCH FOR

Some of the concerns when Harbaugh benched Alex Smith for Kaepernick in 2012 are finally starting to surface. While the move was undeniably a success because San Francisco reached Super Bowl XLVII with the dynamic Kaepernick at the helm, the third-year player has struggled the past two weeks with his top weapons sidelined.

The setback in Seattle during Week 2 could be written off a bit because the Seahawks are so dominant at home and have the NFL's best secondary. Losing to the Colts at Candlestick set off a few alarms, however.

Indianapolis was a playoff team in 2012 thanks in large part to Luck but the defense is still a work in progress so Kaepernick's inability to get anything going even without his field-stretchers has to be a concern and more than a few have speculated Smith, the current starter in Kansas City, who is 22-5-1 in his last 28 NFL starts, would have game-managed San Francisco to a win in that one.

"Football's not easy. There are struggles," Harbaugh said. "That's one of the things you enjoy about the game, that there are struggles. We've got some adversity, there's no question about it. And we'll also have the rare opportunity of staring adversity in the face and whipping it. That's our goal."

Star receiver Michael Crabtree isn't coming back anytime soon and speedy tight end Vernon Davis continues to be slowed by a hamstring injury, although he was back at practice on Monday in a limited fashion indicating there is at least a chance he will be ready by Thursday. His presence will be key because opposing defenders are starting to realize they can sit on veteran Anquan Boldin's routes and neither Kyle Williams or rookie Quinton Patton are consistent enough to pop the top on the other side.

"Well, you never lay it on one spot," Harbaugh said when discussing the receivers. "If we're talking offensively, precision needs to be better and that falls under everybody's purview. So, we'll try one more thing. As always, there's another thing to try and you go back to work and see if you can't improve and fix."

St. Louis has one of the game's best playmakers at cornerback in Janoris Jenkins while Cortland Finnegan is the kind of pesky veteran who can get under the opponent's skin.

"They're a good football team," Fisher said of the Niners. "What they did last year is indicative of that. You don't get to where they got last year without being able to overcome adversity. They were a few plays away from winning the world championship last year. We've got our hands full. Regardless of who's coming or who's not, they're going to be ready to play."

Defensively for San Francisco Smith is gone for now and fellow All-Pro Patrick Willis is also likely to be sidelined during the short week with a groin issue.

Smith, of course, has been one of the NFL's premier pass rushers since being taken by San Francisco with the seventh overall pick of the 2011 draft. He notched 14 sacks during his rookie season, then ranked second in the league with 19 1/2 sacks last year while helping the 49ers to an appearance in the Super Bowl. Willis is a six-time All-Pro and the leader of the San Francisco defensive unit.

Bradford has to be able to take advantage of the situation but needs some kind of running game as a complement. Starter Daryl Richardson injured his foot in the first quarter at Dallas after rushing for just 35 yards on 10 carries in Week 2. Backup Isiah Pead has shown some wiggle as a receiver but not much as a runner at his point.

"Obviously, it's very important," Rams offensive coordinator Brian Schottenheimer said when asked about sparking the run game . "I think you look at both games last year against (the 49ers), we ran the ball pretty well. It's never an easy task against them. They play with great fundamentals and technique, but we need to get the running game going."

OVERALL ANALYSIS

Last year, these two teams tied in their first meeting, which took place in San Francisco, and St. Louis won the rematch on an overtime field goal by Greg Zuerlein.

For whatever reason the Rams tend to play better in divisional action (Rams QB Sam Bradford is 5-1-1 in his past seven starts against NFC West foes) and match up well with the more talented Niners. This may be an example where St. Louis was clearly looking past Dallas a week ago to this game.

"We've been on the losing end of a lot of games (in the rivalry), this organization has," Fisher said. "Now last year, we got our feet back on the map, but I don't think there's a rivalry yet. It's a division opponent. It's a big challenge for us on a short week, but I don't necessarily see it as a rivalry yet. Hopefully, we'll become one."

Sports Network Predicted Outcome: Rams 20, 49ers 17