GLENDALE, Ariz. — Two of the NFL’s boldest head coaches are planning to stick to the script at the slight risk of looking foolish in Super Bowl LVII.

The Chiefs’ Andy Reid ruled out activating a third quarterback, and the Eagles’ Nick Sirianni cavalierly paid lip service to always keeping all options “on the table,” but both are willing to play with the fire that burned the 49ers’ Kyle Shanahan in the NFC Championship game.

“That’s not where we’re at,” Reid said. “We’ve got our couple quarterbacks, and then we’ve got our backup plan. Hopefully we don’t have to get to that backup plan. Chances are that you don’t, but you never know. If you do, you do.”

After Brock Purdy tore the UCL in his throwing arm and Josh Johnson suffered a concussion, the 49ers’ offense was neutered for the final 27 minutes of the NFC title game. A limited Purdy returned because the 49ers chose to activate fourth-string running back Tevin Coleman for one total snap instead of a third-string quarterback. In other cases during the playoffs, teams activated a ninth defensive back or sixth linebacker for a handful of special-teams-only snaps.

“We saw it could happen, so you have to be ready,” Eagles quarterbacks coach Brian Johnson said. “The bigger issue is if you can dress three quarterbacks or not, but in terms of developing the roster, that’s something that’s really important and our head coach does a great job of.”

Why wouldn’t the Eagles then make room for Ian Book or the Chiefs for Shane Buechele to be among their teams’ 48 active players instead of a minimal contributor? The Chiefs could even use one of two practice-squad elevations on fourth-stringer Chris Oladokun.

“That’s a real valid point,” said Chiefs quarterbacks coach Matt Nagy, a former head coach. “We got really close sometimes [with the Bears] to having that third quarterback up. Your special teams coordinator never wants that to happen. You have to weigh that game and maybe the health of a quarterback going into the game — maybe he’s a little banged-up going into the game versus a guy who is never hurt.”

Patrick Mahomes enters the Super Bowl nursing an ankle injury.

“Every week we always have our emergency quarterback go through a script of plays that sometimes you can take for granted and not practice,” Nagy said, likely referring to backup tight end Blake Bell, who completed 150 career passes at Oklahoma before changing positions. “You never want to get to that point.”

A similar situation happened to the Giants in Week 4, when Saquon Barkley took direct snaps and a hobbled Daniel Jones was forced back into the game after backup Tyrod Taylor suffered a concussion. In an era where officials are empowered to pull a quarterback off the field for a concussion test as soon as his head hits the ground, is it as much of a long-shot as it used to be that a third quarterback is needed?

“It’s certainly not,” Nagy said. “When you have your first-string quarterback get hurt and you know you essentially are one play away from disaster, that can be tough.”

Reid and Sirianni both implied that they expect they expect the NFL Competition Committee to revisit the rules in the offseason and perhaps restore the quarterback rule scrapped in 2011: A third-stringer does not count against the active-roster maximum but if he plays before the fourth quarter then the first- and second-stringers cannot return.

“I’m sure that would be a little bit better to watch,” Johnson quipped.