For the first time since Mike Zimmer took over as Vikings head coach in 2014, he won't be on the sideline tonight against the Dallas Cowboys.

But while at some point already having planned a third eye surgery for the day after the upcoming game, a team source told the Star Tribune's Matt Vensel, Zimmer continued to coach every practice and lead every meeting before Thursday's showdown with the NFC-leading Cowboys, General Manager Rick Spielman said on a conference call.

"We're as prepared as we've ever been," Spielman said.

Enter special teams coordinator Mike Priefer, the 50-year-old U.S. Navy and football veteran who is handed the red challenge flags with little notice. That's a silver lining, Spielman offered, unlike a similar scenario the Vikings may have analyzed in the Denver Broncos.

Broncos head coach Gary Kubiak was hospitalized after a Sunday game in October and could not coach that Thursday night. General Manager John Elway announced the next day their special teams coordinator, Joe DeCamillis, would step in as interim head coach. Unlike the Broncos, the Vikings had their coach up until after the week's final practice, Spielman said, before Zimmer's eye required emergency surgery.

Players weren't informed of the possibility Zimmer might not coach the game until Wednesday night, Spielman said. He consulted with ownership and Zimmer, deciding Priefer would coach the upcoming game.

"They are ready and prepared because coach Zimmer coached them all week," Spielman said. "We had a normal week of preparation heading into tonight's game. It's unfortunate this happened, the night before the game today, but I have the utmost confidence in our coaches and players that they will be prepared and ready to go based off the preparation and how they practiced all week."

How long Zimmer will be away from coaching is to be determined, Spielman said. The Vikings have their longest break between games, 10 days, since the Week 6 bye following tonight's kickoff vs. Dallas.

The Vikings have two former head coaches on staff in offensive line coach Tony Sparano and offensive coordinator Pat Shurmur, but pegged Priefer in order to keep the offensive and defensive staff focused on their sides, Spielman said, and his experience with game management situations.

"I think the one thing that is significant about special teams coaches is they're always thinking about game management situations, whether to kick a field goal. Do you take a safety or do you punt out of the end zone?" Spielman said. "I know Priefer's leadership. Usually special teams coaches are the ones speaking to the whole team during special teams meetings because it's not divided into offense and defense. It's the whole team. And I don't have any doubt that Mike Priefer will do a great job tonight."

It's relatively unfamiliar territory for Priefer, who has coached some of the NFL's best special teams units with the Vikings since his arrival in 2011.

The Vikings field two of the league's best return teams while punter Jeff Locke is enjoying a career best year. This season, the team did release former All-Pro kicker Blair Walsh, whom Priefer vouched for during the 2012 draft. Priefer is still well respected around Winter Park and kept his job after a team-imposed, three-game suspension in 2014 after an independent investigation into claims he made a homophobic remark during the 2012 season.

"Under the circumstances for tonight, because this happened a day before the game, less than 12 hours ago," Spielman said. "I talked to ownership about it last night and confirmed with him this morning that myself and coach Zimmer felt this was the best approach to take for tonight's game."