Injuries: Packers fear Jake Ryan has serious knee issue

The Green Bay Packers could begin the regular season without a starting linebacker.

Coach Mike McCarthy said Jake Ryan continues to undergo tests, but the fear is Ryan suffered a "serious knee injury" during Monday's practice, NFL Network Insider Ian Rapoport reported Tuesday, via a source informed of the situation.

The potential loss of Ryan, who was carted off the practice field Monday, would leave the Packers with a major hole in the middle of the defense.

Ryan started 12 games in 2017 and proved effective against the run, totaling 81 tackles on the season. Over the past three seasons, Ryan has appeared in 43 games with 27 starts, including 22 over the past two seasons, while totaling 213 tackles.

Green Bay used a third-round pick on rookie Oren Burks, and he could have the first shot to replace Ryan alongside Blake Martinez. The other option on the current roster could be second-year pro Ahmad Thomas, who spent time on the Packers' practice squad in 2017.

While the Packers wait for news on Ryan, there is reason for optimism for safety Kentrell Brice, who also left Monday's practice on a cart.

X-rays were negative for a break and there will be a clearer picture on his return when the swelling goes down, Rapoport reported.

Here are other injuries we're tracking from training camp Tuesday:

1. Philadelphia EaglesPro Bowl guard Brandon Brooks was at practice today participating in full after being sent to the hospital during Sunday's practice because of dehydration, NFL Network's James Palmer reported.

2. San Francisco 49ers defensive end Arik Armstead is week to week as he battles a hamstring injury, per NBC Sports Bay Area.

3. Denver Broncos coach Vance Joseph said he expects cornerback Tramaine Brock (hamstring) to miss about a week, according to Nicki Jhabvala for The Athletic.

4. Seattle Seahawks coach Pete Carroll says wide receiverDoug Baldwin is dealing with "a little bit of a sore knee" that will keep him sidelined for a couple weeks. In addition, defensive end Dion Jordan has a "stress issue" in his leg that will keep him out "awhile," Carroll said. A source informed of the situation told NFL Network's Tom Pelissero the stress issue is located in his shin.

5. Los Angeles Chargers cornerback Tevor Williams was helped off the field after suffering an apparent ankle injury during practice, per multiple reporters.

6. The Tennessee Titans placed cornerback Tye Smith on injured reserve with an undisclosed injury.

7. The Oakland Raiders waived offensive lineman Vadal Alexander on a non-football injury designation.