SANTA CLARA –- Coach Kyle Shanahan admits to being mad after the 49ers’ 29-22 loss to the Atlanta Falcons last week.

It took him a full day to come to grips with the 49ers' loss and put it into perspective.

And here is the pertinent fact he passed along to his team: That game did not ruin the 49ers’ season.

“When you do lose a game you should win at the end of the year, it can cost you a lot,” Shanahan said on "49eres Game Plan," which airs Saturday at 1 p.m. on NBC Bay Area (Ch. 3).

“Fortunately, we put in a lot of work this year and we’ve had a hell of a season so far. And we earned, through our record and the situation we’re in, that one slip-up did not cost us as much as it should’ve cost us if we didn’t put the work in.”

With two weeks remaining in the regular season, the 49ers still can assure themselves the NFC West title and home-field advantage throughout the NFC playoffs with victories over the Los Angeles Rams and the Seattle Seahawks to close out the regular season.

First up, the 49ers must take care of business against the Rams (8-6) on Saturday night at Levi’s Stadium.

Here are five important 49ers to watch in the key Week 16 game:

5. OL Daniel Brunskill

The Rams feature the league’s best defensive lineman.

Aaron Donald will line up just about everywhere on the defensive line. And on third downs, he will target the opposing offensive lineman he knows he can best exploit.

It appears as if the 49ers do not expect right guard Mike Person to be available to play Saturday night while he is limited by a neck condition. He went through limited practice this week.

First-year player Daniel Brunskill is expected to step into the lineup to take over for Person.

Brunskill has proven to be a valuable backup for the 49ers. He started five games at right tackle and one game at left tackle earlier this season while Mike McGlinchey and Joe Staley were out with injuries.

Brunskill has a chance to work his way into the 49ers’ starting lineup next season, and his best chance of getting there could be at guard. His work Saturday night against Donald could be a springboard to bigger things in the future.

4. QB Jimmy Garoppolo

The Rams’ defense will not make it easy on Jimmy Garoppolo, as defensive coordinator Wade Phillips will try to confuse the 49ers quarterback with a variety of zone coverages. The 49ers do not expect Los Angeles to play a lot of man defense.

Garoppolo has to be decisive as he checks it down to the open receivers for short gains. He must make the right reads while also being sure he gets rid of the ball before Donald and the Rams' pass rush gets to him.

Garoppolo, named as an NFC Pro Bowl alternate this week, is having the best season for a 49ers quarterback in a long time. He completed 69.1 percent of his passes for 3,445 yards with 26 touchdowns and 11 interceptions through 14 games. His passer rating is 102.8.

The last 49ers quarterback to finish a full season with a higher passer rating was Hall of Famer Steve Young, who registered a 104.7 mark in 1997.

Garoppolo has played at a consistently high level in the second half of the season, and he has to keep it going in order for the 49ers to earn home-field advantage. Shanahan said on "49ers Game Plan" that he is confident Garoppolo can help the 49ers win any game that they put in his hands. This might be one of those games.

3. CB K’Waun Williams

The 49ers’ defense played without three of its top five players in the secondary against the Falcons last week. Strong safety Jaquiski Tartt remains out of action with fractured ribs, but Richard Sherman and K’Waun Williams are back.

Sherman is a five-time Pro Bowler, so his value is known. But Williams is an integral part of the team’s defense due to his ability to cover the slot receiver in zone and man coverages, while also being a sure tackler.

Williams will face a stiff challenge Saturday, as he goes against Rams receiver Cooper Kupp. Kupp leads the Rams this season with 83 receptions for 1,031 yards and eight touchdowns. Kupp and New England Patriots receiver Julian Edelman are tied atop the NFL with most receptions (61) out of the slot position, according to Pro Football Focus.

Williams, who missed last week’s game due to a concussion, will not be eased back into the action. Rams quarterback Jared Goff and Kupp will test him repeatedly on third downs as Los Angeles looks to extend drives with passes to its go-to receiver.

2. WR Deebo Samuel

The 49ers figure to face a lot of zone coverage, which will make hitting plays down the field very difficult. Samuel is at his best when he is catching passes underneath, then turning into a running back.

Samuel has turned into a valuable part of the team’s passing game. He is the 49ers' top wideout this season, catching 48 passes for 669 yards and three touchdowns. Samuel still makes a lot of rookie mistakes, but he has earned Shanahan’s trust as an every-down player. As has veteran receiver Emmanuel Sanders.

Last week, Garoppolo targeted tight end George Kittle on half of his 34 passing attempts. The Rams certainly will do their best to take Kittle out of the game, which should give Samuel some space to operate and turn short passes into longer gains. Samuel and A.J. Brown of the Tennessee Titans are the only rookies in the league who average more than 8 yards run-after-the-catch this season.

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1. DE Nick Bosa

Until Dee Ford returns from a hamstring and quadriceps injuries, the 49ers probably are not capable of being the same dominant defense that showed up repeatedly earlier in the season. The 49ers only have three sacks in the past three games.

Bosa, chosen to the Pro Bowl this week, has attracted a lot of attention as a rookie, and for good reason. He ranks second in the league among rookies and second on the 49ers, behind Arik Armstead, with nine sacks. The 49ers need an edge rusher to help close out games, and Bosa is the most likely candidate.

On Saturday, it will be a classic matchup of youth vs. experience. Bosa will go up against 14-year veteran Andrew Whitworth, a player against whom he matched up in October. Bosa said he received a learning lesson in October when he went up against Whitworth.

“He’s so good at holding and doing all these small things, just grabbing onto you,” Bosa said. “I might think I’m having a great bull rush. But in reality, he’s got my two pads and he’s pulling me to the ground with him. He just uses what you do well against you, and he’s been doing it for a long time.”