Dec. 20—Time has run out for Baker Mayfield and most of the Browns on their lengthy reserve/COVID list.

Starting safety John Johnson III tested negative on the morning of Dec. 20, but no one else did. The result means Mayfield and backup quarterback Case Keenum plus starting wide receiver Jarvis Landry, tight end Austin Hooper, left tackle Jedrick Wills, defensive end Jadeveon Clowney, defensive tackle Malik McDowell, safeties Ronny Harrison and Grant Delpit, linebacker Mack Wilson and return specialist JoJo Natson, among others, will be unavailable when the Browns host the Las Vegas Raiders at 5 p.m.

Head coach Kevin Stefanski also tested positive again. It means he will not be on the sideline and that special teams coach Mike Priefer will serve as head coach. Offensive coordinator Alex Van Pelt will call plays.

Seven players were activated from the practice squad to help fill out the still-depleted roster: cornerback Brian Allen, guard Hjalte Froholdt, defensive end Joe Jackson, running back John Kelly, cornerback Herb Miller, safety Jovante Moffatt and safety Tedric Thompson.

The Browns started preparing for this situation when Mayfield and Stefanski first tested positive for COVID on Dec. 15. Nick Mullens, who had been on the practice squad, will start at quarterback against the Raiders in a game critical to the Browns' chances of making the playoffs. Mullens stared eight games for the 49ers in 2018 and eight more last season. He is 5-11 as a starter.

The Browns are 7-6. They will be tied with the Bengals and Ravens for first place in the AFC North if they beat the Raiders. An 8-6 mark would keep them in the thick of the wildcard race in the conference. A loss would drop them to no higher than 11th in the AFC seeding with the Dolphins and Broncos at 7-7.