(CNN)No head coach, starting quarterback, or full practice, and 18 players on the Covid-19 list -- pre-match preparations don't come any tougher for the Cleveland Browns.
Ravaged Cleveland Browns set to play through Covid absences as NFL notes 'substantial increase in positive cases'
Hosting the Las Vegas Raiders on Saturday in a game with potentially crucial ramifications for their playoff ambitions, the Browns announced that 11 of those sidelined are regular starters.
First-choice quarterback Baker Mayfield was one of six players added to the listed absentees on Wednesday, joining head coach Kevin Stefanski and acting running backs coach Ryan Cordell in testing positive.
How many of those currently sidelined will be cleared in time for Saturday remains to be seen -- pending further testing -- but regardless, the outbreak has wreaked havoc on pre-match preparations.
The Browns have been unable to hold a full, standard practice session this week, breaking into three separate groups for walkthroughs on Wednesday.
Despite the severity of the Browns outbreak, at a league meeting in Texas on Wednesday, NFL commissioner Roger Goodell said that there are no current plans to postpone the game.
"We feel confident with continuing changes and adaptations to our protocols that we can do that," he told reporters.
NFL chief medical officer Dr. Allen Sills admitted that the Browns situation coincided with a "substantial increase in positive cases" throughout the league, highlighting that the pandemic had entered "a new phase."
Sills reasoned that the Omicron variant, declining immunity, and the increased potency of respiratory illnesses in winter-time had all contributed to an increase in cases, but noted two key differences in the recent surge of cases.
"First of all, far more players affected than staff," Sills said.
"We have about twice as many staff as we do players who are testing and so typically we've run a higher ratio of staff cases to player cases -- over the past four to five days we've seen that ratio inverted."
The second, "most important" distinction, Sills said, was a large proportion of asymptomatic or mild cases.
"Just looking at our data for the last two days, two-thirds of people have no symptoms at all that have been diagnosed," Sills said.
"The others have very mild symptoms -- symptoms that might not even cause them to seek a test in ordinary circumstances."
During the meeting, the NFL encouraged players to get vaccinated and get booster shots.
On December 2, the league stated that 94.4% of its players were vaccinated along with "nearly 100%" of other NFL personnel.
"I think everybody's entirely focused on how do we stay safe, how do we do that in the best possible way," Goodell said.
"Dr. Sills has been consistent, as well as NFLPA medical experts and our independent experts ... the best way to do that is vaccines and boosters. That is not a foolproof mechanism, but it's certainly the best way to do that."
For Stefanski and the Browns, this unprecedented scenario is "just another obstacle." As 18 doors close, many more open up for previously underused players to make an impact.
"We have really good leadership on this team with our players, and I really believe that they are going to focus on the task at hand," Stefanski said.
"We have guys on this roster who we have been developing, who are in the meetings and are diligent about preparation. If we are calling on them this week, they will be ready, that is what they do. That is their job."
One such player is back-up quarterback Case Keenum who -- in the absence of Mayfield -- suddenly faces the prospect of leading the offense in a pivotal game.
A crucial 24-22 victory over the AFC North leading Baltimore Ravens (8-5) last weekend moved the Browns to within a win of their defeated opponents, who face a tough test in the Green Bay Packers (10-3) on Sunday.
Keenum oversaw a victory in the absence of an injured Mayfield in Week 7, throwing for 199 yards and a touchdown in a 17-14 defeat of the Denver Broncos. Two months on, he prepares for duty under wildly different circumstances.
"It's pretty unique," Keenum said. "I would say nothing really surprises me about the NFL these days.
"It just adds one more thing to the portfolio, if you will, of strange occurrences and different situations that come up."
Special teams coordinator Mike Priefer -- set to deputize as acting head coach should Stefanski be ruled out -- has zero doubts on Keenum's capability to see the team through.
"Thank god we have Case Keenum," Priefer said.
"If you had a real young quarterback, an inexperienced quarterback, it might be tougher.
"Case is going to run the gameplan exactly how it should be run, and I know the whole team has confidence in him."