The Week 4 showdown with the Denver Broncos is steadily approaching for the San Francisco 49ers.

It’s a matchup that won’t be as easy for the 49ers as it was the last two weeks against the Miami Dolphins and the Arizona Cardinals. Denver is a fairly tough team that will put up a fight.

However, they aren’t some formidable team that will be super difficult to beat. In fact, they have one weakness that the 49ers will be chopping at the bits, and no, it’s not just Bo Nix.

49ers must take advantage of Broncos’ Weakness Broncos' run defense

Sep 20, 2026; Denver, Colorado, USA; Denver Broncos linebacker Alex Singleton (49) makes a tackle on Jacksonville Jaguars running back Chris Rodriguez Jr. (24) during the third quarter at Empower Field at Mile High. Mandatory Credit: Ron Chenoy-Imagn Images | IMAGN IMAGES via Reuters Connect

Denver’s weakness is surprisingly on their defense, specifically against the run. They are horrendous at stopping the run. The Broncos allow the third-most rushing yards per game (143.7) and per play (5.1).

They also have the seventh-worst team-run stuff rate (11.8%) and the 11th-most runs of 10-plus yards (9), per Next Gen Stats. Denver’s defense gets propped up as being great, and while it does deserve some praise, they have a clear Achilles heel.

It favors the 49ers significantly because Kyle Shanahan loves to run the ball. Now, the 49ers have favored passing this season over running the ball. It makes sense given how sharp Brock Purdy has been.

But this is a game where they have to unleash Christian McCaffrey and rookie Kaelon Black. The Broncos are begging them to run it on them. It would be malpractice for them to not attack it often.

Besides, the strength of the Broncos’ defense is their secondary. Passing it against arguably the best cornerback in the NFL, Patrick Surtain, will be tough, especially with Mike Evans hurt or out. 

Talanoa Hufanga will be a threat as well, but I think Kyle Shanahan will know how to attack him. He’s not as great in coverage as he’s made out to be, as he can be fooled into biting on plays.

In any case, Shanahan will surely know that running is the key to defeating the Broncos. Not only will it work since Denver’s weak against it, but it’ll help them pass the ball smoothly.

I’d expect McCaffrey to have his first 100-yard rushing game and for Black to be efficient as well. If the Broncos somehow are better against the run, which I’d imagine they stack the box, it’ll be better for the 49ers.

In a battle between Shanahan and Broncos defensive coordinator Vance Joseph, Shanahan has the upper hand.

The 49ers can make the Broncos look like an easy win on Sunday if they can take advantage of their weakness.

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