BOSTON (CBS) — If Wednesday and Thursday didn’t call for some concern, then Friday’s Patriots practice attendance signaled that it’s officially time to ring some alarm bells in New England.

When the Patriots hit the practice field on Friday, they once again did so without Trent Brown, Isaiah Wynn, Mike Onwenu and Shaq Mason. That quartet makes up four-fifth of the team’s starting offensive line, and the absences spell a lot of trouble for Sunday’s game in Houston.

That status could improve for Wynn and Onwenu, who are in the league’s COVID-19 protocols. The details of their situations aren’t exactly known, so it’s possible that one or both could be eligible to play Sunday if they satisfy the conditions of the protocols.

Brown and Mason, though, were ruled out in Friday afternoon’s injury report.

Brown has played just one series this year before suffering a calf injury that’s caused him to now miss four games. Mason is out with an abdominal injury.

The absence of those four linemen has left David Andrews as the only member of the starting offensive line to practice this week. Ted Karras, who filled in for Onwenu on Sunday night, figures to start at left guard. What the Patriots do elsewhere is anyone’s guess.

“I think today will help clear some of that up,” Bill Belichick said Friday. “But whoever has the opportunity I’m sure will make the most of it. And I know the guys that didn’t practice are working as hard as they can to be ready to go, and the guys that did are likewise preparing. And if they get an opportunity, I think they’ll be ready to go, too. So we’ll just see how it all plays out. I don’t know.”

The full injury report is below.

PATRIOTS

OUT
T Trent Brown (calf)
G Shaq Mason (abdomen)
CB Shaun Wade (concussion)

QUESTIONABLE
LB Ja’Whaun Bentley (shoulder)
DB Cody Davis (knee)
S Kyle Dugger (hamstring)
K Nick Folk (knee)
CB Jonathan Jones (ankle)
DB Jalen Mills (hamstring)
LB Ronnie Perkins (ankle)
LB Kyle Van Noy (groin)

TEXANS

OUT
RB Rex Burkhead (hip)
QB Deshaun Watson (not injury related)

QUESTIONABLE
WR Danny Amendola (thigh)
T Marcus Cannon (back)