Philadelphia must beat New Orleans on Saturday, and San Francisco has to top Green Bay on Sunday afternoon.
If those tumblers fall, it will bring the San Francisco 49ers back to Seattle on Jan. 11 for a divisional round playoff game at CenturyLink Field.
Hopefully there will be enough time to do a full seismic retrofit of the region's buildings and bridges, because a third meeting between these teams this season might cause tectonic shifting -- players colliding like continental plates, and fans just coming entirely undone.
There was a skip in the cosmic cogs in last season's playoffs, when a curious 30-second gap in the machinery allowed Atlanta to derail the Seahawks' path to the NFC title game against San Francisco.
This might be an even better payoff, deferred as it is, allowing the competitive antagonism to build to a higher boil as the teams split another pair of games this season.
The Seahawks' 27-9 win over St. Louis on Sunday gave them the NFC West title and home-field advantage through the playoffs.
As it now shapes up, a New Orleans win Saturday would send the Saints back to Seattle. But a Philly victory causes the Green Bay-San Francisco winner to come out to CenturyLink.
Fans might have different perspectives on this, but the 49ers matchup with the Hawks might be so appealing that it would be worth fans' rooting for the San Francisco win over the Packers. If that's not against 12th Man by-laws.
Seattle handled the Niners 29-3 here in September, while the Niners dealt them a painful 19-17 loss on Dec. 8, which kept the Hawks from securing the division title and home-field advantage for three more weeks.
The Niners (12-4) are the only NFC playoff team with a win over the Seahawks this season and have reeled off six straight.
Meanwhile, a return of the Saints to Seattle would be anticlimactic, as the Seahawks spanked them 34-7 on Dec. 2, holding Drew Brees to 147 passing yards -- a season-low of less than half his usual production.
The Saints (11-5) are stumbling, too, having won just twice in five December games.
The Hawks haven't faced Green Bay since the famed Sept. 24, 2012, game when Golden Tate pulled in the disputed Hail Mary pass on the final play to give the Hawks a 14-12 win.
A week of replaying that moment would grow tedious.
The Packers could be dangerous, though, coming in at 8-7-1, a record made irrelevant by the 71/2-game absence of quarterback Aaron Rodgers. While Rodgers healed from a broken collarbone, the Packers won just three games.
Now returned to health, Rodgers could give Green Bay the kind of late lift that sometimes fuels strong playoff runs.
New Orleans or Green Bay might make it easier for the Seahawks to advance to the NFC title game, and maybe that's a consideration for fans as they send out their wishes this week.
But maybe taking on the Niners would be the best thing they could do. By virtue of the best record in the NFC, the Hawks earned a bye into the division round, giving them a week to heal, self-scout, refine techniques, and dismantle the videos of possible opponents.
San Francisco, meanwhile, has to devise a way to stop Rodgers and live another week.
Adding to the challenge for the Niners, though, is the typical burden of the wild-card teams. They have to travel to Green Bay for a Sunday afternoon game, but then turn around and be in Seattle for the early game Saturday afternoon.
Two road games on a short week? Weather issues possibly compounding both? Facing the fans at Lambeau Field to earn the right to be tossed out in front of a frothing 12th Man crowd at CenturyLink? And having to take on a team that had outscored them 71-16 in the two preceding meetings there?
Yes, there might be easier paths to the Super Bowl, but using a bitter rival as a stepping stone might add to the experience.
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