The San Francisco 49ers have already locked up the NFC's No. 1 seed for the playoffs. With their postseason fate sealed, the 49ers are keeping it safe with Brock Purdy for Week 18.

Sam Darnold will start in place of Purdy against the Los Angeles Rams, via Cam Inman of the San Jose Mercury. The Rams are implementing a similar strategy, starting Carson Wentz over Matt Stafford in Week 18.

With a win over the Washington Commanders in Week 17, San Francisco moved to 12-4, clinching the NFC's top seed. A win or loss against the Rams won't change that. Rather than having their starting quarterback play, Kyle Shanahan and company will give Darnold a chance, preserving Purdy's health.

Purdy will end the regular season having thrown for 4,280 yards, 31 touchdowns and 11 interceptions. He is a serious contender for MVP and made 49ers history by breaking Jeff Garcia's record for single season passing yardage. San Francisco has found a gem in Purdy.

However, the 49ers have been hitting playoff speedbumps. They've reached the NFC Championship the past two years in a row. They'll be looking to make it a three-peat in 2024. But San Francisco wants more to just make it, but this time actually win.

A healthy Brock Purdy is key to that success. As is Christian McCaffrey, who has already been ruled out. The 49ers have been dominant throughout the season and have nothing left to prove in terms of their talent. They'll get a postseason tune up with the Rams in Week 18. But the 49ers are much more focused on the actual playoffs.