Stern warning from NFL officials to its teams Monday ... the league is demanding coaches wear their masks properly -- or they could face punishment!!
Due to the coronavirus pandemic ... the NFL has ordered all essential personnel on the sidelines to wear masks AT ALL TIMES.
The problem? Cameras caught several prominent coaches Sunday -- including Rams head man Sean McVay and Raiders leader Jon Gruden -- wearing the face coverings improperly around their necks.
In a league memo from Troy Vincent, obtained by multiple media outlets, the league exec said that's straight-up just unacceptable.
"The face covering must be worn as designed so that it securely fits across the wearer's nose and mouth to prevent the transmission of the virus," Vincent said.
"Failure to adhere to this requirement will result in accountability measures being imposed against offending individuals and/or clubs."
In addition to McVay and Gruden, cameras also caught Lions head coach Matt Patricia and Saints head coach Sean Payton improperly wearing their masks.
Dallas Cowboys head coach Mike McCarthy, meanwhile, did not wear one for the pregame national anthem Sunday night ... but added it during his team's game against the Rams.
Stay safe, people!