The 26-21 win that ensured the San Francisco 49ers wouldn't have to travel for the entire month of January wasn't clean or pretty. San Francisco clinched the top seed by literally one inch, and only after giving up a big lead and then getting some late breaks from both the officials and Seahawks head coach Pete Carroll.

But road wins over experienced, playoff-caliber opponents are almost never pretty, rarely clean. The key is that, with its fate essentially on the line, a San Francisco team that just arrived on the national stage as a contender confirmed it isn't too green to gut out tough wins under playoff-like spotlights.

All season, many of those who watched as San Francisco continually put together elite performances couldn't help but wonder if the 49ers were destined to undergo the rite of passage we often see from trendy new teams. Just like the breakout 2017 Los Angeles Rams and the breakout 2018 Chicago Bears, it was fair to wonder if the 2019 49ers were due for a wake-up call in January, if not earlier.

After all, the 49ers were just a four-win team last season. Their quarterback, Jimmy Garoppolo, just completed his first full season as a healthy NFL starter. The roster and the coaching staff are relatively young, fresh and inexperienced.

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That aforementioned Rams team was also coming off a 4-12 season when it suddenly won the NFC West and then suddenly went one-and-done in the 2017 playoffs. And that aforementioned Bears squad was coming off a 5-11 campaign when it rose up and won the NFC North before quickly departing from the postseason on Wild Card Weekend.

These 49ers might be different. They won't have to worry about the wild-card round thanks to Sunday's fortitude-drenched performance in a hostile environment against a Super Bowl-winning coach and a superstar quarterback.

Again, not a work of art. But without key defensive players Dee Ford and Jaquiski Tartt, and with the receiving corps and the offensive line banged up, they got past a team that might be the best in professional football in close games.

Following the game, 49ers head coach Kyle Shanahan said he wished "it wouldn't have been that close at the end," but that's often what the Seahawks do. Quarterback Russell Wilson was magical at times down the stretch as an 11th one-score victory of the season almost felt inevitable for Seattle.

The 49ers primarily deserve credit for building a 13-0 first-half lead to insure themselves in anticipation of that second-half Seahawks run, but also for responding to back-to-back momentum-swaying second-half Seattle touchdowns with touchdown drives of their own.

Just seconds after Wilson threw a touchdown pass to Tyler Lockett to cut San Francisco's lead to 13-7 in the third quarter, Garoppolo quieted a famously cacophonous crowd with a 49-yard completion to fullback Kyle Juszczyk, and four plays later the 49ers were in the end zone with more insurance.

And after a fourth-quarter Marshawn Lynch touchdown made it a one-score game again, Garoppolo and Co. traveled 75 yards in seven plays in just over four minutes to again pad their lead.

The Seahawks still nearly pulled it off, and they probably would have done so if not for a bad non-call and a silly delay of game penalty in the dying moments of the fourth quarter, but the Seahawks had no margin for error at that point because of the work San Francisco put in earlier. The 49ers dominated a desperate and savvy opponent on the road throughout the first half, and they were just good enough in the second half to earn a critical advantage in the new year.

Maybe that was their rite of passage.

Maybe they had to lose a heartbreaker on the road to the Super Bowl favorite Baltimore Ravens to gain the mettle necessary to win a 48-46 track meet one week later against the juggernaut New Orleans Saints on the road. Maybe they needed a slap in the face at home against the Atlanta Falcons in Week 15 to dig deep for consecutive tough divisional victories to close out the regular season. And maybe they needed to nearly choke in Seattle just because it's an experience they'll be even more ready for next time around.

Ever since the 49ers lost to Seattle in agonizing fashion and then crushed the Green Bay Packers on national television in November, it feels like this team has been growing up at hyper-speed. They've encountered such a wide variety of highs and lows that they're likely better prepared than other breakout teams from the recent past to handle their first playoff run.

Of course, it helps that they'll now officially be at home for the entire NFC playoffs and that they'll have two weeks to rest, recover and game-plan for what will be Shanahan's first postseason game as a head coach and Garoppolo's first as a starting quarterback.

These 49ers basically saw it all this season, and they prevailed. They're not only one of the most talented teams in the NFL, and they're not only in their conference's driver's seat now, but it's starting to look as though they've got championship-level mental strength as well.

If you were still doubting the 49ers prior to Week 17, now's the time to reconsider that stance.

Brad Gagnon has covered the NFL for Bleacher Report since 2012.