NFL warns coaches about not using face covering on sidelines

The NFL sent a memo Monday reminding teams and coaches that it's important to follow the league's guidelines regarding wearing face coverings on the sidelines.

"Failure to adhere to this requirement will result in accountability measures being imposed against offending individuals and/or clubs," league executive Troy Vincent wrote, according to Tom Pelissero of NFL Network.

While the Thursday and Sunday games during Week 1 seemingly went off without a hitch, TV broadcasts highlighted some coaches who weren't taking the face-covering protocols as seriously as others.

Kansas City Chiefs head coach Andy Reid notably struggled with his face shield during the season opener, with the equipment fogging up during his team's win over the Houston Texans.

Other coaches opted for masks, but some were seen pulling the covering down to make play calls or talk to players and other staff members.

All players and coaches passed their COVID-19 tests prior to Week 1.