One game, the N.F.C. championship, stands between the star-studded Los Angeles Rams becoming the second team in N.F.L. history — following the Tampa Bay Buccaneers last year — to play the Super Bowl in its home venue.

In their path, though, is the San Francisco 49ers, a division rival who has beaten them in their six previous meetings, including a come-from-behind win in Week 18 that allowed the 49ers to enter the postseason as a No-6-seeded wild card. Since then, San Francisco has toppled the Cowboys and the top-seeded Green Bay Packers, both on the road, in statement wins that have the 49ers on course to make their second Super Bowl appearance in three years despite being the lowest remaining seed in the playoffs.

Sunday’s showdown between two California-based teams that are incredibly familiar with one another provide a slew of story lines and matchups to watch for.

The head coaches of both teams, San Francisco’s Kyle Shanahan and Los Angeles’s Sean McVay, were both assistants under Mike Shanahan on Washington’s 2013 team. Kyle, that team’s offensive coordinator was later replaced in that job by McVay, who was Washington’s tight ends coach when they overlapped.

As head coaches, Shanahan, 42, has had the upper hand on McVay, 36, but the Rams this year have closed the talent gap by aggressively building out their roster. General manager Les Snead traded much of the team’s draft capital to acquire the cornerback Jalen Ramsey in 2019, and then quarterback Matthew Stafford and linebacker Von Miller this season. Wide receiver Odell Beckham Jr. also joined midway through the year as a free agent.

Though his 17 regular-season interceptions tied for first in the league, Stafford also threw for 4,886 yards and 41 touchdowns, both top-three figures. Cooper Kupp led the league in yards (1,947), receptions (145) and touchdowns (16), and Beckham morphed into a reliable second option, giving the Rams the big-play options that McVay loves to use to stretch defenses.

Stafford can be goaded into mistakes, however, and the 49ers’ defense bottled up the Rams for long stretches in their two games this season. The front line of Nick Bosa and Arik Armstead, in addition to Arden Key, are a powerful force. Key in particular has been a surprise. Signed as a free agent after three years with the Raiders, Key had 6.5 sacks, 17 quarterback hits and five tackles for a loss. Collectively this postseason, the defensive front helped hold two of the best offenses in the league — Dallas and Green Bay — to 27 points, and did so on the road in both cases.

Los Angeles’s offensive line allowed seven sacks in the last two games against San Francisco, and must protect Stafford from the pass rush so receivers can exploit the 49ers’ secondary, a weak spot.

By contrast, San Francisco’s offense is predicated on exotic motions and play-action passes across the middle of the field, the latter of which is enabled by Jimmy Garoppolo’s quick release (in their last two meetings, Garoppolo’s throws were clocked as leaving his right hand within 2.35 seconds, according to N.F.L. NextGen Stats).

Targeting receivers over the middle of the field, including tight end Kittle, could help the 49ers to neutralize Ramsey, the Rams’ best cornerback. Garoppolo has exploited the Rams’ linebackers in his two games against the Rams this season, completing 29 of 36 passes for 320 yards and three scores when throwing over the middle of the field.

None of that plan works without San Francisco establishing the run and this season that task has hinged on Deebo Samuel, the third-year wide receiver who has become one of the most electric and essential offensive players in the N.F.L. In their two meetings against the Rams during the regular season, the 49ers ran the ball 75 times. In the second half and overtime of their matchup in week 18, the 49ers rushed for more than 100 yards.

In last week’s 13-10 victory over the Green Bay Packers, Samuel took a helmet-first hit to his right knee, raising concerns about his health. But he was not listed on the team’s injury report and practiced this week, signs that team will expect him to carry his usual load. If he is slowed for Sunday’s game, the 49ers will have to rely more heavily on Kittle, rookie running back Elijah Mitchell and receiver Brandon Aiyuk.

San Francisco’s run game is the key differentiator to the N.F.C. championship game. With it, the 49ers can counteract the Rams' tremendous defense, keeping defensive lineman Aaron Donald, Miller and Ramsey guessing about their targets. Without an effective ground game, Garoppolo could be forced into predictable passing situations, allowing the menacing Rams to run free.