After four weeks of warm ups, the New England Patriots are set to open their regular season schedule Sunday against the Pittsburgh Steelers. However, they’ll be doing so without some notable players due to injury.

With a combination of nagging issues and season-enders, the Patriots took some hits in the injury department this preseason -- most recently with first-round pick N’Keal Harry landing on injured reserve.

Here’s a rundown of who got hurt during the preseason and what their outlook is.

(Note: The Patriots are not required by the NFL to disclose injuries during the preseason and take full advantage of that.)

INJURED RESERVE (can return)

These are players who were placed on injured reserve after the Sept. 1 roster deadline. The Patriots bring back up to two players from this list after Week 8.

WR N’Keal Harry (Lower leg) - Harry was spun down awkwardly in the Patriots’ preseason opener and has gone on to miss the team’s next two games. However, his injury had been reported as being "very minor.” Additionally, Harry wound up returning to practice. However, things took a turn this weekend when the Patriots placed him on injured reserve, wiping out at least the first half of his rookie season.

INJURED RESERVE (ineligible to return)

These are players who were placed on IR before Sept. 1. They are ineligible to return this season. Their year is officially over.

DE Derek Rivers (Undisclosed) - Rivers left the preseason game against the Titans under his own power with an apparent injury. He was not seen since and the nature of his injury was unclear.

LB Brandon King (Torn quad) - King was carted off the field following a punt return against the Panthers in the preseason, suffering a torn quad.

C David Andrews (Blood Clot) - After being hospitalized for a blood clot with his lung, the Patriots captain was shut down for the season and is now focusing on 2020.

OL Hjalte Froholdt (Shoulder) - The rookie went down in visible pain in the preseason finale and was placed on season-ending IR a couple days later.

DB Malik Gant (Leg) - Gant suffered painful-looking leg injury during the preseason and was carted off the field.

DB D’Angelo Ross (Undisclosed) - The undrafted rookie went down during training camp and cleared waivers, resulting in him landing back on IR in New England.

ONGOING INJURIES

TE Ben Watson (Concussion) - Watson was hit late in the head by Panthers safety Eric Reid and remained lying down on the field after. He’s was in the NFL’s concussion protocol, according to The Boston Globe’s Jim McBride. Since Watson was already set to serve a four-game suspension at the start of the season, his return time line is unclear.

RB Damien Harris (Undisclosed) - Harris was banged up early in the team’s preseason game against the Titans and did not return to the game. For now, the nature of his injury and his timeline for return remain unclear.

DE Shilique Calhoun (Undisclosed) - Calhoun had been getting first-team reps in practice until he got hurt against the preseason game against the Titans. Calhoun has not been seen since, but did make the team’s final 53-man roster.

WR Cameron Meredith (Knee) - Meredith has been on the PUP list as he continues to work his way back from a major injury sustained in 2017.

RETURNED FROM INJURY

WR Julian Edelman (Broken thumb) - Edelman reportedly broke his thumb while playing catch this offseason. He was activated off the non-football injury list during the preseason. He appeared to shake his hand in discomfort during the preseason finale, but is expected to be OK.

WR Demaryius Thomas (Torn Achilles) - Thomas suffered a season-ending Achilles injury, which comes with a long-term recovery time, last season. However, he was activated off the NFI list and made his preseason debut against the Giants. He was briefly cut at the roster deadline, be appeared to be set to start the season.