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The Seattle Seahawks are the definition of an underdog. Written off before the season with Russell Wilson traded and Geno Smith becoming the starting quarterback, few gave the Seahawks an opportunity to compete in an NFC West that had three playoff teams from a season before. Seattle defied the odds by finishing with a winning record and getting into the postseason on the final day of the regular season, needing a win and a Green Bay Packers loss to qualify, 

Geno Smith had an excellent year in his first season as the Seahawks starting quarterback. Smith led the NFL in completion percentage (69.8%) while setting the franchise record for passing yards in a season (4,282). Smith also threw for 30 touchdowns to 11 interceptions, finishing with a 100.9 passer rating as he's set to make his first playoff start. 

While Smith has been successful in his first season as Seattle's starter, the Seahawks had excellent contributions from their rookie class. Charles Cross and Abraham Lucas both started 16 of a possible 17 games at offensive tackle, running back Kenneth Walker rushed for 1,000-plus yards (led rookie class with 1,050 yards), cornerback Tariq Woolen tied for the NFL lead in interceptions, and fellow cornerback Coby Bryant forced four fumbles to lead the rookie class. Seattle's rookie class trailed only the Houston Texans in starts (70) and the Chicago Bears in snaps (5,671) -- yet Seattle is in the playoffs and those two have the top two picks in the draft. 

The future is bright in Seattle, but can the Seahawks upset a San Francisco 49ers team that beat it twice during the season? The odds aren't in Seattle's favor, yet here's how it can emerge victorious.

Featured Game | San Francisco 49ers vs. Seattle Seahawks

1. Brock Purdy faces same opponent for first time

Brock Purdy
SF • QB • #13
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Purdy has been everything the 49ers could ask for in his five starts -- and more. Not only are the 49ers 5-0 in Purdy's five starts, but they also led the NFL in points per game (33.6) in those games. Purdy has arguably been one of the best quarterbacks in the NFL, tying for the league lead in pass touchdowns (11), yards per attempt (8.9), and passer rating (119.0). Purdy's passer rating was the highest for a quarterback in his first five starts since Kurt Warner in 1999.  

While Purdy has played at a high level, he hasn't faced an opponent twice. Purdy had a full game against the Seahawks and played well, yet Clint Hurtt's defense has a full 60 minutes of game film to study tendencies on how to rattle Purdy and force a seventh-round rookie quarterback to make enough mistakes to give Seattle a chance. 

Purdy was 17 of 26 for 217 yards and two touchdowns against Seattle in his first game against them, but was 5 of 10 with a touchdown (127.5 passer rating) in the second half. The Seahawks will have to hold Purdy to a low completion rate again if they wish to have a chance at the upset. 

2. Inclement weather frees up Kenneth Walker, run game

Kenneth Walker III
SEA • RB • #9
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An equalizer in Saturday's rematch will be the weather, which will resemble Bay Area conditions this time of year. The weather forecast is calling for "potential for flooding rains," with winds of 15 to 25 miles per hour. These conditions play into Seattle's favor as well as San Francisco's.

The Seahawks are a good run blocking team and have the game's best rookie running back in Walker, who had 228 carries for 1,050 yards and nine rushing touchdowns on the season. In his past three games, Walker had 78 carries for 354 yards, averaging 4.5 yards per carry. 

Walker was the backup running back to Rashaad Penny in the first meeting, but had only 12 carries for 47 yards in the Week 15 matchup. The 49ers run defense is second in yards allowed (77.7) and yards per carry allowed (3.4), so Walker will be the one Seattle will have to rely on to get the yards with the passing conditions less than ideal. 

Seattle is 4-1 when Walker runs for at least 100 yards this season. If he hits that mark in those conditions, Seattle has a shot at the upset.

3. History doesn't fully favor team that sweeps in regular season

Seattle will be facing San Francisco for the third time this season, which will be the 24th time there has been a third meeting between teams in a season in which one team has swept the other in a regular season series. The 49ers dominated the Seahawks in the first two meetings by a 48-20 margin, but that doesn't guarantee a victory in the third matchup.

The winner of the first two matchups is 14-9 in the third meeting. While the .609 win percentage is good, a regular season sweep doesn't guarantee victory in the playoffs. The 49ers-Seahawks matchup does greatly favor the 49ers, but Seattle did just play this team five weeks ago and got a good look how San Francisco looks with Purdy and Christian McCaffrey -- aspects of the game it didn't get to see on a short week in Week 15. 

Seattle has at least some hope it can upset San Francisco based on the history of a third meeting in a season. San Francisco has a lot of advantages, but the 49ers can't let the Seahawks hang around, either -- especially with them being an upset-team with nothing to lose as the No. 7 seed.