New York, New York - With just days to spare before the 2021 NFL regular season kicks off, several players find themselves having to stay away from their respective teams after testing positive for Covid-19, in turn forcing their coaching staffs to call audibles well before game day.

The NFL has an even more complicated aspect to their injury lineup heading into the new season: those football players who are deemed inactive due to the league’s Covid-19 protocols.

It only takes one positive test to put an entire roster in potential danger – in more ways than one.

Take the best player to stand on the offensive line for the Dallas Cowboys, offensive lineman Zach Martin (30). The six-time Pro Bowler is perhaps the biggest name to have tested positive this week for the coronavirus.

NFL 2024 NFL Draft: Most cringe-worthy moments from the big night

Martin's primary job is to help protect his franchise quarterback Dak Prescott from defenders who are looking to sack him. Prescott is coming into this season after missing most of last year with a gruesome leg injury and has spent much of this past preseason nursing an uneasy throwing arm.

Now, it’s not always Martin’s fault if a defender gets their hands on his quarterback behind the line of scrimmage, but as long as he's on the field, Prescott can play at least a little more comfortably.

Cowboys head coach Mike McCarthy was typically straightforward in an interview with ESPN on Sunday: "Hey, this is the world we live in right now."

The Cowboys will be without Martin, and how many other Cowboys might still test positive between now and their season opener on Thursday night against the Tampa Bay Buccaneers remains to be seen.

Other teams in the league come into Week 1 slightly shorthanded due to players on the Covid-19 injured reserve list.

New York Jets wide receiver Jamison Crowder, who is vaccinated, has been on his team’s Covid-19 reserve list since this past Friday. As of Monday, he was reported to still have Covid-related symptoms, leaving his availability for the Jets’ opener on Sunday, still up in the air.

The Kansas City Chiefs will begin their run at a third-straight Super Bowl appearance on Monday night, but they might be without one of the best defensive players in Tyrann Mathieu, who is also vaccinated against the virus. Mathieu is asymptomatic but has yet to properly return negative test results.

Vaccinated players who aren’t showing any symptoms need to produce two negative tests 24 hours apart in order to be granted permission to return to the team, per NFL protocols.

The Miami Dolphins currently have two players on their Covid list, with offensive lineman Austin Jackson and backup tight end Adam Shaheen set to potentially miss their own season opener against the Patriots.

Jackson is thought to be held out as a precautionary measure, but it’s Shaheen who’s the bigger liability, given that he is reportedly the one who tested positive while also being unvaccinated.

Players that didn't take the shot must quarantine for 10 days and abide by the same negative testing regulation as the unvaccinated players, according to the current NFL protocols.

Shaheen is among the NFL population who is adamant that taking the option to get vaccinated is a "personal choice", and that the league isn’t "going to strong-arm me into doing something for more freedom when this is such a changing atmosphere, and they're already taking away freedoms of the unvaccinated guys," as he explained to ESPN on Monday.

The 2021 NFL season kicks off with the defending Super Bowl champion Tampa Bay Buccaneers hosting the Dallas Cowboys on Thursday night.