Starter Riley Nelson suffered a rib injury in last week's loss at San Jose State and did not practice Monday and Tuesday. Lark took all of the reps at QB.
"We have a lot of confidence in (Lark)," said wide receiver Cody Hoffman. "He's backed up Riley all year and he's come in games when we've had big leads. We know what to expect from him and we know the kind of guy that he can be. We'll just rally behind him if he is the starter."
Offensive coordinator Brandon Doman said the game plan won't change much with Lark under center.
"Not a lot," he said. "Obviously there won't be as much movement and quarterback run-game stuff."
"We run the BYU offense. It's the same," Lark said. "The coaches will call the plays that I'm the most comfortable with, that I've run over the years. Riley likes some plays better and I like some better. They'll tailor that for me during practice throughout the week."
The Aggies have struggled defensively this season, and Doman is cautiously optimistic that the Cougars will be able to move the ball.
"I hope we could, but we've been a little up and down," he said. "I'd like to see us have a consistent week of practice and I'd like to see us have a consistent game As long as we're consistent and secure the football, I'll feel like it was a successful Saturday."
PLAYING IN LAS CRUCES: BYU coach Bronco Mendenhall is familiar with Las Cruces. He coached a number of games here when he was the defensive coordinator at New Mexico. The Lobos and Aggies, of course, are in-state rivals.
What kind of atmosphere does he expect Saturday?
"Different when I was at UNM, because that was more like BYU-Utah State, Utah State-Utah — more interstate, packed house, bragging rights, fierce environment," he said. "I'm sure this will be different."
The Cougars expect New Mexico State to be fired up for this contest.
"They play hard," Lark said of the Aggies. "This is their last (home) game, so we know they're going to come out ready to play. We've just got to prepare for what they do. Most importantly, we've got to focus on what we do."
"They coaches said it's going to be a pretty tough atmosphere, with it being their last (home) game of the year," Hoffman said. " They're going to come out, of course, and want to win. We'll just play hard and not take them lightly by any means."