The Vikings will not try to replace safety Harrison Smith on Sunday against the Jaguars.

“You can’t,” defensive backs coach Jerry Gray said. “You can’t go mimic what Harrison does.”

While the Pro Bowl safety will leave a massive void in the Vikings defense, Friday’s quiz among defensive backs should help solidify confidence in his stand-in. Second-year safety Anthony Harris is expected to make his third career start Sunday with Smith (sprained ankle) ruled out.

At the end of each week, Gray and assistant coach Jonathan Gannon randomly call out defensive backs to test their knowledge of the game plan and opponent. Harris, the 25-year-old undrafted Virginia product stepping in for one of the NFL’s highest-paid safeties, was perfect during Friday’s test of the Vikings game plan and the Jaguars offense.

“I think it was two [questions],” Harris said. “I take pride in, even when I’m not being asked the question, knowing the answer to whoever he’s asking, whether he’s asking a safety or a corner.

“Usually, I’m pretty good at that. I think that’s one of my strengths.”

“The DB quiz,” as cornerback Xavier Rhodes dubbed it, is a derivative of the “Jeopardy” game Gray brought to the Vikings defensive backs three years ago. Sometimes they’ll take the quizzes a step further and separate safeties and cornerbacks into teams to see which group knows that week’s game plan the best. Topics include their own altered coverages for the upcoming game or an opponent’s route concepts.

“If you get it, you get it,” Rhodes said. “If you don’t, we’ll give you hell about it.”

It’s a teaching method Gray picked up in Seattle while he coached Seahawks defensive backs during the 2010 season. Six years later, the style of coaching has helped both prepare Harris and give coaches a sense of where his head’s at entering EverBank Field in Jacksonville.

“At the beginning, guys are a little reluctant because they’re like, ‘Aw, man, you’re trying to embarrass me,’ ” Gray said. “But really, it’s my job to figure out what you don’t know, so if I don’t get it right on Friday, I’ve got time to correct it until Sunday.”

Gray should have little to reinforce with Harris before starting him alongside Andrew Sendejo.

The Vikings’ fourth-ranked scoring defense is difficult to predict, in part, because of Smith’s versatility. Rosters across the NFL couldn’t replace Smith’s instincts, his crushing hits or his ability to blitz on one snap and cover a tight end on the next.

They’ll make do altering the game plan around Harris, whom coach Mike Zimmer summarizes as a smart player using intellect to make up for athletic limitations. After he was promoted from the practice squad to make two spot starts last season, Harris earned a 53-man roster spot this summer over veteran Michael Griffin.

Active for all 12 games this season, Harris has only seen extended defensive snaps when he replaced seventh-round rookie Jayron Kearse in Chicago. Kearse was yanked on the opening drive after he was out of position on a long run.

“Anthony is a little quicker with understanding the different nuances of things he has to do,” Zimmer said.

Emphasize the quick. During Friday quiz sessions, fellow defensive backs or coaches will shout “ball snapped!” if the player takes too long to answer.

“You get put on the spot in front of the room or your peers,” cornerback Captain Munnerlyn said. “It’s like ‘Ah, ah, umm …’ and ‘ball snap!’ … If the ball is snapped, the offense is not going to wait on you to realize what you’re doing.”

There’s nowhere to hide in Vikings defensive back meetings. And Harris is fine being targeted, crediting a “good memory” for being able to learn and retain opponent formations and tendencies.

“If it’s something we put in all week and by Friday you don’t know what you’re doing, it makes you look bad,” Munnerlyn said. “Nobody wants to look bad, so it’s a good setup for the team.”