49ers vs. Cardinals Final Score Prediction for NFL Week 18 (Can 49ers Win Without Purdy?)

San Francisco 49ers quarterback Brock Purdy is injured, moving the odds for their Week 18 clash with the Arizona Cardinals.

San Francisco 49ers quarterback Brock Purdy is injured, moving the odds for their Week 18 clash with the Arizona Cardinals. / Sergio Estrada-Imagn Images

The NFC West was turned upside down this season, as the San Francisco 49ers have been eliminated from the playoffs just one season removed from a trip to the Super Bowl.

Plus, the Arizona Cardinals had first place in the NFC West in their sights before a collapse in recent weeks, including a loss to the Carolina Panthers in Week 16 that eliminated them from postseason contention. 

49ers quarterback Brock Purdy was injured in a high-scoring affair on Sunday night in a loss to Detroit, and he’s expected to miss Week 18. 

So, oddsmakers have set the 49ers as underdogs in the latest odds. 

Neither of these teams has anything to play for (outside of draft position), but we can still bet on this matchup. I’m attempting to predict the final score of this Week 18 contest using the latest odds movement as a guide. 

49ers vs. Cardinals Odds, Spread and Total

Odds via DraftKings Sportsbook.

Spread

• 49ers +4 (-112)
• Cardinals -4 (-108)

Moneyline

• 49ers: +164
• Cardinals: -198

Total

• 42.5 (Over -110/Under -110)

After opening as favorites in this game, the 49ers are now four-point underdogs with the news that Brock Purdy (elbow) won’t play in Week 18. 

That likely means that Josh Dobbs will get the start for San Francisco, although neither of these teams has anything to play for in terms of playoff position. 

49ers vs. Cardinals Final Score Prediction

Had Purdy been able to suit up, I likely would have bet on the 49ers to win this game, and SI Betting’s Iain MacMillan pointed out earlier this week in his Road to 272 that Purdy being in a contract year is a pretty big motivator for him to have shown out – if he was able to go – on Sunday. 

Instead, we may have to trust the Cardinals, who have struggled in December with Kyler Murray at quarterback. In Murray’s career, he’s just 8-15 straight up, and Arizona blew a chance to spoil the Rams’ season in Week 17. 

I still think Josh Dobbs can keep the 49ers afloat in this one, but San Francisco has dealt with so many injuries in 2024 that I wouldn't be shocked to see it play things safe with some of the starters on this roster.

I’ll take the Cards to win a low-scoring affair, but getting the points with the 49ers is certainly intriguing now that this spread has moved through the key number of three. 

Final Score Prediction: Cardinals 16, 49ers 13

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Odds refresh periodically and are subject to change.

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