The Vikings offense received an unexpected refresher course on exotic blitzes in their second preseason game Friday night in Buffalo.

Now the Vikings defense gets its turn to face an unconventional scheme this week.

The Vikings will get a taste of read-option offense Sunday night against the San Francisco 49ers in the third and most important preseason game. Niners quarterback Colin Kaepernick headlines a group of dual-threat quarterbacks whose success running the option has caused NFL coaches to search for ideas on how to defend what could become a new trend.

The Vikings are treating this preseason game as a dress rehearsal for the regular season because very few starters, if any, will play in the final tuneup. As an added bonus, they get to game plan for Kaepernick and the read option, which will serve as an appetizer for the main course in the regular season.

Their schedule includes four quarterbacks who run some variation of the read option: Carolina's Cam Newton, Washington's Robert Griffin III, Seattle's Russell Wilson and Philadelphia's Michael Vick. Those quarterbacks utilize the option in varying degrees, but they're all capable of creating havoc with their legs.

Kaepernick is equally scary on the move — just ask the Green Bay Packers — which is why Vikings coach Leslie Frazier believes this preseason game could be "very valuable" for his defense, assuming Kaepernick shows off that part of his repertoire.

"To get that [experience] in the preseason," Frazier said, "we're hoping it's going to pay dividends down the road."

The Vikings won't simulate a normal work week in terms of preparing a complete game plan. But the defense will spend time analyzing how to defend the read option, essentially making this a test run for what lies ahead.

"We face almost every one of those quarterbacks that run this year, so this will be good practice," safety Harrison Smith said. "A lot of times you'll play a team and you won't really count the quarterback in the run game. This is one where we'll have to always acknowledge what [Kaepernick] is doing back there. It will be good for us to see how disciplined we can be."

The read option, in essence, requires the quarterback to make snap decisions on whether to hand the ball off or keep it himself, depending on how the defense reacts. That scheme puts extra stress on defenses because it forces them to account for a quarterback who can run — and usually run well. It's even more effective when the quarterback also is an accurate passer.

"If teams have quarterbacks that have the ability to take off with the ball, they're going to try and put that in their game because it's one more thing you have to game plan for," Smith said. "One more thing you have to worry about."

The NFL is known as a copycat league and the success of Kaepernick, Griffin and Wilson last season in operating the read option could inspire other teams to consider quarterbacks with similar skill sets.

Kaepernick, in particular, sent defensive coordinators scurrying for answers after he shredded the Packers defense for an NFL quarterback-record 181 rushing yards in their playoff game. The Packers looked thoroughly confused and helpless in trying to contain Kaepernick, who according to ESPN research, gained 178 of his 181 yards before being touched.

In response to that performance and the overall trend, defensive coordinators contacted college coaches for help because option football remains prevalent at that level.

Frazier confirmed Sunday that he visited with Kaepernick's college coach, Chris Ault, to discuss the read option. Ault created the "Pistol" offense at Nevada, which incorporates the option. Several NFL teams reportedly contacted Ault this spring before the Kansas City Chiefs hired him as a consultant.

"We talked about that offense and how it derived," Frazier said. "He gave me a little bit of the history and we talked about some things."

Presumably, Frazier wanted to know its vulnerabilities and the best way to defend it. The key, Harrison said, is every player being fundamentally sound.

"It's just discipline," he said. "But it's a lot harder than it sounds."