San Francisco 49ers and Seattle Seahawks players probably don’t need much external motivation to get them going every time the teams meet.

But if the 49ers need any, there is a lot they can dip in to:

• The memory of Seattle’s 13-3 victory over the 49ers at Levi’s Stadium on Jan. 3 — which gave the Seahawks the NFC West division title, the No. 1 seed in the conference playoffs and led to a raucous, cigar-smoke-filled celebration afterward in the visitors’ locker room.

• The memory of Seattle’s 41-6 victory over the 49ers two weeks later at Lumen Field in the divisional playoff round. Maybe the only two San Francisco fans still left in the building by the end were father and son Vinod and Neal Khosla, then 49ers minority owners and now controlling owners of the Seahawks.

• The sight of Seattle’s 29-13 Super Bowl victory over the Patriots on Feb. 8 that led to another Seahawks cigar-smoke, champagne-filled celebration, but this time in the 49ers’ locker room at Levi’s Stadium.

Seahawks players say they know those things may be on the collective mind of the 49ers when the teams meet Sunday at Lumen Field. But they say the intensity of the rivalry and the stakes of the game — early control of the NFC West — mean more.

“They might feel a certain way,” Seahawks safety Julian Love said. “Regardless of what happened last year, we don’t like them, they don’t like us, straight up. They might not like us a little bit more because of what happened at the end of last season. But it is what it is.

“We know it’s going to be a fist fight against a division opponent. That’s all of them. We don’t like anybody in our division, so that’s understood. It doesn’t have to be explained. You can throw fuel to the fire, (but) the fire should be burning pretty high already.”

Indeed, this is a game that seems to have enough on its own.

The healthy-again 49ers are 4-0 and boast a statistical profile backing up the claim that they may be the best team in the NFL. They are averaging 6.8 yards per play (best in the NFL), allowing 4.8 (third-best) and have outscored opponents 122-64 (an NFL-best point differential of plus-58).

The Seahawks are in second place in the West at 3-1. They were upset two weeks ago at Washington and are coming off a sloppy, 30-23 victory over the Chargers last Sunday in which they were assessed 150 penalty yards, most in team history.

Another similar effort by the Seahawks could have them running uphill the rest of the season.

Let’s preview the matchup.

When, where: 1:25 p.m. Sunday, Lumen Field.

TV: FOX (Channel 13 in Seattle) Kevin Burkhardt (play-by-play), Tom Brady (analyst), Erin Andrews, Tom Rinaldi (sidelines).

Most recent game in series: As noted above, the Seahawks are riding a two-game overall winning streak. But the 49ers have won four consecutive regular-season games at Lumen.

Point spread: Seahawks favored by 3.

Key injuries: Every Seahawk listed as a starter on the two-deep is set to play. That includes safety Ty Okada, who is set to make his season debut after sitting out the first four games because of a hamstring injury and defensive lineman Leonard Williams, shaking off an ankle injury suffered against the Chargers. Backup running back George Holani (rib, knee) is questionable. 

The 49ers will be without several key players, notably defensive end Nick Bosa (knee/calf), fullback Kyle Juszczyk (knee) and safety Marcus Sigle (ankle). 

Can top-ranked Seahawks defense slow top-ranked 49ers offense?

The Seahawks have allowed the fewest yards in the NFL (246.8), and the 49ers have scored the second-most points (30.5 average).

Seahawks defenders were peeved enough after giving up 17 second-half points to the Chargers last week to call a players-only meeting Monday. The 49ers, meanwhile, surely spent the offseason coming up with new wrinkles for Seattle after scoring just nine points in the final two games against the Seahawks.

Something will have to give.

New-look 49ers receiving corps vs. Seahawks secondary 

With his receiving corps again healthy, 49ers quarterback Brock Purdy is again playing like an MVP candidate.

Four players — Mike Evans (17), Christian McCaffrey (16), George Kittle (16) and Deebo Samuel (14) — have combined for 63 of the 49ers’ 79 receptions this season.

Of those four, only McCaffrey played in the divisional playoff game.

“None of what happened last year matters,” said Seattle linebacker Ernest Jones IV. “It’s a new year, new season. They’ve got a hell of a group.”

Seahawks offensive line

For all the understandable focus on Seattle’s running-back situation, what’s obviously also critical to making the team’s rushing attack go is the offensive line. Though the Seahawks are averaging just 3.9 yards per attempt, 19th in the NFL, they rank ninth in run blocking by Pro Football Focus. And though the 49ers rank ninth in yards allowed per carry at 3.7, they are just 21st in PFF’s run defense metric. In other words, for each team, the raw stats may not tell the whole story and there could be opportunities for the Seahawks if their line can get a good push.

8

That’s how many quarters the 49ers have gone without scoring a touchdown against the Seahawks, dating to the fourth quarter of the regular-season opener a year ago.

In Seattle’s 13-3 win in the regular-season finale and 41-6 win in the divisional playoff round, the 49ers had 19 combined possessions and scored just three times on field goals.

The other possessions ended in five punts, five turnovers on downs, two interceptions, one fumble, one punt, one drive ending at the end of the half and another at the end of the game.

Expect someone to have pointed that out to 49ers coach Kyle Shanahan this week.

Can Seahawks sack 49ers QB Purdy?

Due to how well the 49ers’ line is playing, the offense executing well and Purdy’s mobility, San Francisco has yet to allow a sack this season. The 49ers are the first team in 21 seasons and the fifth team ever not to allow a sack in their first four games of a season, joining the 2005 Indianapolis Colts, 1984 and 1989 Miami Dolphins, and 1975 St. Louis Cardinals.

Defensive lineman Williams being healthy will help the Seahawks’ cause.

Will JSN and Lenoir renew acquaintances?

Remember when Jaxon Smith-Njigba, Seattle’s standout receiver, and Deommodore Lenoir, San Francisco’s starting cornerback, exchanged a little back-and-forth before the regular-season finale last year? JSN noted that it’s “hard to respond back to all my fans” after Lenoir said he wanted to shadow Smith-Njigba in the game.

Lenoir this week said only that “he’s a great player, much respect, but when we’re in between the lines it’s competition always.”

49ers defensive coordinator Raheem Morris said Lenoir won’t get assigned the primary responsibility for Smith-Njigba but added, “There will definitely be moments where they’ll have a chance to get together.”

For what it’s worth, they didn’t match up much last season. Via Pro Football Focus, Smith-Njigba had one catch for 4 yards on three targets when covered by Lenoir last season.

Seahawks 23, 49ers 21

As players and coaches reiterated all week, this is indeed a new season, and this game won’t be 41-6. But this is the 49ers’ first true road game of the season and Seahawks coach Mike Macdonald has shown he has defensive schemes that work against the 49ers. If the Seahawks defense cleans up its penalty act and quarterback Sam Darnold avoids turnovers, they should get a critical win.