Jerry Rangel occasionally texts his son Garret the same three words.

“Preparation equals success.” A Rangel family mantra. Not that Garret needs a reminder. He’s been hearing the sage advice before he got a phone.

“That was drilled into him since he was in grade school,” Jerry said.

The advice resonates now as much as ever. Last week, an injury to senior Spencer Sanders thrusted Garret, a true freshman OSU quarterback, from highly touted third-stringer into the starter spot at Kansas.

Next? Perhaps salvaging the Cowboys’ suddenly floundering season, depending on the Sanders’ status.

Will he start against Iowa State on Saturday? For the rest of the season? Coach Mike Gundy won’t tip his hand. But those who have known Rangel the longest say he is ready for the moment.

“He’s been ready since he stepped foot on that campus,” said Christy Rangel, Garret’s mom. “I can just tell you that that’s his mental state.”

Jeff Rayburn, Rangel’s high school coach at Frisco Lone Star, said it is difficult to unnerve Rangel.

“He’s going to take all the good and all the bad and all the ugly, but he wants it on his shoulders,” Rayburn said. “And that’s somebody that everybody will follow.

“And so I don’t think there’s anything you can put him in that’s going to rattle him.”

Rangel’s debut against Kansas was a mixed bag. He threw 40 passes in a 37-16 loss. He threw for 304 yards and two touchdowns, but also tossed three interceptions.

Senior center Preston Wilson, who placed fault for the interceptions on the entire offense, said he was impressed with Rangel’s spot-start performance.

“I think he handled it the best way he could possibly,” Wilson said. “He came in, he didn’t act scared. He didn’t act timid and stuff, but he was also willing to accept advice from older guys. He knows he’s having to step into a quarterback role and that’s a huge role and you do have to be vocal and be loud.”

While evaluating Rangel on the sideline, Gundy said he thought the young quarterback was calm and demonstrated a clear understanding of what was going on.

“I thought he played good, made some plays,” Gundy said. “Obviously, he had some mistakes, but that’s gonna happen when you’re young. He had some turnovers and things that were unfortunate, but I liked the way he competed, liked the way he threw the ball at times.”

Jerry and Christy said Rangel’s composure may stem in part from his experience. He started playing flag football at 4, and while no toddler truly runs an offense, Rangel was the quarterback even then.

“The minute he did anything, he was a competitor,” Christy said. “He was born with it. Because it’s something you can’t really teach.”

Rangel shares competitiveness with his mom.

It is where “the heart of a lion” — the other Rangel family mantra — comes in. Whether playing Monopoly or pingpong, Rangel’s parents never let him win. He had to earn it, especially in ping-pong.

“(Christy) would do the Forrest Gump moves and Garret would get frustrated at that,” Jerry said. “Then all of a sudden he would excel at that and come back and triple whatever Christy just did.”

Rangel’s sudden rise up depth charts is nothing new. When he enrolled at Frisco Lone Star High School, he expected to be put on the ninth-grade team. Instead, Jerry and Christy got the unexpected pleasure of watching him start on junior varsity.

After a few games on JV his freshman year, he was elevated to varsity.

Rangel seized the starting job his sophomore year. Three games into the season, he faced a daunting task. A road game against Highland Park, the No. 1 team in the state.

“It’s a hostile environment,” Rayburn said.

Highland Park had not lost a home game to an in-state team since 1998. Rangel ended the streak. He threw a 45-yard strike on the first play of the game, connecting with future Oklahoma receiver Marvin Mims for a touchdown.

Lone Star pulled out a 30-19 victory against Highland Park, the three-time defending state champs.

“From there I think Garret’s confidence really grew,” Rayburn said.

Three different offensive coordinators coached Rangel in high school. Christy said he studied for hours, in preparation for when he would be quizzed on the offense in front of his teammates.

As for free time, he plays Madden and reads sports books.

“He knows the mental preparation that comes with this game,” Jerry said. “He’s not going to be one of those guys clowning around out there. He never has been.”

The Cowboys aren’t anointing Rangel the long-term starter yet. Gundy said he will continue to evaluate Rangel and fellow backup Gunnar Gundy, the coach’s son, before making any decisions.

If Sanders is healthy enough to play, the battle becomes a moot point.

The chance to preserve Rangel’s redshirt is another complicating factor. If Rangel plays in three more games, he cannot be redshirted, as NCAA rules allow a player to appear in four games and still maintain redshirt status.

Rayburn doesn’t think the uncertainty will faze Rangel.

“Garret Rangel will never blink and he will never flinch,” Rayburn said. “I don’t care what game it is, how big the moment is. That’s what kind of separates him so many people.

“He thrives in that type of environment.”