NFL teams have worked all preseason to hit their stride in time for the kickoff of Week 1.

They'll all be looking to dethrone the two-time defending Super Bowl champion Kansas City Chiefs, who once again look like they'll be among the NFL's elite. However, there are still far too many unknowns before we can even think about what the playoff picture might look like. (Then again, that won't stop us from trying to predict how the 2024 season will unfold anyway.)

One of the greatest variables this season will be injuries, and not all of the NFL's 32 teams will go into their season-openers 100% healthy.

Here's a look at some of the most notable Week 1 injury concerns:

RB Christian McCaffrey, San Francisco 49ers

McCaffrey tweaked his calf during camp in early August and didn't play in any of the Niners' preseason games. However, he's been practicing on a regular basis and should be good to go on Monday night vs. the Jets.

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QB Justin Herbert, Los Angeles Chargers

Herbert was diagnosed with a plantar fascia injury in his foot in late July and was in a walking boot for two weeks. He has gradually been ramping up his activity and should be fine to start Sunday, despite his questionable designation.

TE Mark Andrews, Baltimore Ravens

Andrews was involved in a car accident Aug. 14, but the Ravens said he was not injured. Still, he did not participate in practices for two weeks before returning to action last Friday. That will give him a full week of on-field work before Baltimore's opener against Kansas City on Thursday.

WR Marquise Brown, Kansas City Chiefs

"Hollywood" sustained an injury to his shoulder area Aug. 10 and coach Andy Reid said he doesn't expect Brown to be available for the opener Thursday. The Chiefs chose not to put him on injured reserve to start the season, an indication they expect him back by Week 4. In the meantime, Kansas City did sign veteran wideout JuJu Smith-Schuster for depth.

WR Ricky Pearsall, San Francisco 49ers

The 49ers placed Pearsall on the reserve/NFI list — meaning he will miss at least the first four games of the regular season — as the rookie recovers from a gunshot wound to his chest.

Pearsall already had been dealing with a shoulder injury that had limited his participation in training camp.

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