Jaguars Must Solve 49ers Defense to Stay Competitive in Week 4

Sunday is a grand opportunity for the Jacksonville Jaguars. They will travel to the West Coast to take on the 3-0 San Francisco 49ers, a team that, when healthy, can be a serious threat in the NFL due to their creativity on offense and discipline defensively. Under defensive coordinator Robert Saleh, the 49ers defense is playing as well as ever.

However, the Jaguars have experience playing against fast, aggressive, and disciplined defensive units in practice every day, particularly in a recent game against the Houston Texans. Jacksonville's offense, led by head coach Liam Coen and offensive coordinator Grant Udinski, will be challenged by a defense that, despite losing star pass rusher Nick Bosa, will be nagging all game long.

Udinski shares the difficulties of San Francisco's defense

Udinski Jag — Jacksonville Jaguars offensive coordinator Grant Udinski answers questions from the media after an NFL training camp session at the Miller Electric Center, Wednesday, Aug. 6, 2025, in Jacksonville, Fla. [Corey Perrine/Florida Times-Union] | Corey Perrine/Florida Times-Union / USA TODAY NETWORK via Imagn Images

"I think problems on all three levels," said the first-year offensive coordinator, who has faced Saleh's style of defense. Even with Bosa done for the year, the 49ers have quality playmakers at every level, including All-Pro linebacker Fred Warner, rookie pass rusher Mykel Williams, and rookie safety Marcus Sigle, who has emerged as a key player on the backend to start the season.

"The pass rush, you see those guys getting off the ball, then the linebackers, Warner obviously makes plays all over the field, sideline to sideline, pass game, run game, shooting gaps, in coverage, tackling screens," Udinski said. "Then at the third level, they challenge guys in the back end, track the ball, ball skills."

Warner Jag — Sep 21, 2025; Santa Clara, California, USA; San Francisco 49ers middle linebacker Fred Warner (54) takes the field prior to a game against the Arizona Cardinals at Levi's Stadium. Mandatory Credit: Cary Edmondson-Imagn Images | Cary Edmondson-Imagn Images

The 49ers' defense under Saleh, whether this year or during his first tenure, has remained productive and plays an urgent need for true rallying to the football. Udinski said there is a reason for that:

"There's a reason the defense has put up the numbers they put up and perform the way they performed, really because of the way they execute and the guys they have and the way they play," Udinski explained.

When asked if the first quarter is a projection without Bosa, Udinski explained that even if there is truth to it, Saleh is rotating his players along the defensive front and there are plays this season where he hasn't been on the field, giving the Jaguars some images of what to expect.

Saleh 49er — Sep 7, 2025; Seattle, Washington, USA; San Francisco 49ers defensive coordinator Robert Saleh, left, and head coach Kyle Shanahan, right, exit the locker room during pregame warmups against the Seattle Seahawks at Lumen Field. Mandatory Credit: Joe Nicholson-Imagn Images | Joe Nicholson-Imagn Images

"You expect things to be a little bit similar, a little bit different in some regards, but it's not like losing a quarterback or something on offense where every single snap is a complete overhaul of the offense," Udinski said. "Certainly, his loss will be felt because he's such a phenomenal player, but you feel things out, but you've seen a little bit of how the defense looks without him out there."

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