The San Francisco 49ers will square off with their NFC West rivals, the Los Angeles Rams, for the right to go to Super Bowl LVI. They are coming off the heels of a massive upset, beating Aaron Rodgers and the Green Bay Packers at Lambeau Field. Not many gave them a shot last week, and many feel the same again this week. That's despite the fact that San Francisco has beaten Los Angeles six straight games.

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There are a lot of key players on both sides of the ball, on both teams. But there is one key X-Factor for San Francisco that needs to play well for them to pull off the upset again.

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49ers X-Factor vs Los Angeles Rams

Nick Bosa and the defensive line

Yes, it's accurate that the 49ers would stand a much greater chance at winning if Jimmy Garoppolo plays well. But historically, the data does not support the idea that he is an X-Factor for this team to succeed.

One only needs to look to last week vs. the Packers. Garoppolo did not play very well. He completed just 11 passes for 131 yards without a touchdown and one interception. The interception was a killer too. The Niners were driving late in the half and he threw the pick at the goal line.

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Even the running game never got going last week, and they still beat Green Bay.

If you look beyond that, when San Francisco made their run to the Super Bowl two years ago, they did it with Garoppolo being a spectator. Well, technically he played on the field. But you probably didn't notice as the team seemingly ran the ball every down, both in the NFC Championship and the Super Bowl.

During the current six-game winning streak against the Rams, San Francisco has held Los Angeles to 18 points per game. Their defense has been the difference in these matchups. The 49ers have sacked Matthew Stafford seven times in their two meetings this year. They have pressured him countless other times.

Bosa has turned it in the post season. He has seven sacks and 31 pressures with a Pro Football Focus pass rushing grade of 90.0.

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I expect San Francisco's offense to struggle to get points again. So, in order for the 49ers to pull off another upset, their defensive line will have to continue to dominate.