Keenan Reynolds, who helped propel Navy past Air Force last weekend, will become the first freshman to start at quarterback for the Midshipmen since 1991. (David Zalubowski/Associated Press)

When Navy freshman quarterback Keenan Reynolds stepped onto the field at Falcon Stadium on Saturday in place of starter Trey Miller, the Midshipmen were trailing Air Force, 21-13, in the fourth quarter and in danger of having their season unravel with a fourth straight loss to an Football Bowl Subdivision opponent.

With a partisan crowd of nearly 40,000 making the surroundings as inhospitable as possible, Reynolds, according to teammates, commanded the huddle with authority and moxie that belied his youth in directing a scoring drive that ended with his 15-yard touchdown burst and fullback Noah Copeland’s tying two-point conversion run.

Then in overtime, Reynolds marched Navy into the end zone on the opening possession, and the defense made it stand for a 28-21 victory in the first leg of the Commander-in-Chief’s Trophy.

This week, Reynolds said he was “at peace” at the time in spite of the noise and unfavorable circumstances.

“I don’t remember a guy coming in and playing like that before, just taking in all the factors,” Navy Coach Ken Niumatalolo said. “All any of us could say was, ‘Wow.’ I mean that was big-time.”

On Friday night on the road against Central Michigan, Reynolds is set to become the first freshman to start at quarterback for Navy since Jim Kubiak played five games in 1991. Niumatalolo made the announcement following practice on Wednesday after considering not only Reynolds’s showing, but also Miller’s performance before he aggravated the left ankle he initially hurt in the season opener against Notre Dame.

Through 31 / 2 quarters against the Falcons, Miller ran for 110 yards on 18 carries and completed all three of his pass attempts. He had by far the most productive outing of his career in reaching 100 rushing yards against an FBS opponent for the first time.

Most important, Miller did not have a turnover after logging 10 through the first four games. The only fumble Navy had against Air Force came in overtime, when Reynolds lost the ball at the 1 trying to break the plane of the goal line. Right guard Jake Zuzek fell on the loose ball in the end zone for the touchdown.

The victory gave Navy (2-3) the early edge in regaining the Commander-in-Chief’s Trophy it relinquished to Air Force three years ago after having won it a service academy-record seven consecutive times beginning in 2003. It also avenged last year’s 35-34 overtime loss to the Falcons at Navy-Marine Corps Memorial Stadium.

“He just understood it was his time to go out there and do the right thing,” offensive coordinator Ivin Jasper said of Miller, who worked on protecting the football as late as into pregame warmups. “It was just emphasizing [ball security] but also him going out there and doing it.”

Miller was wearing a walking boot covering his left calf and ankle as he watched practice on Monday, when he said his expectation was to be able to play against the Chippewas (2-3). Central Michigan has lost two in a row and fell to Navy, 38-37, the last time the teams played two years ago in Annapolis.

Miller practiced on Tuesday but was unable to do so on Wednesday, making the decision a bit more practical for Niumatalolo. Miller, a junior, had started every game this season, but Reynolds has played in four of the five. The only game in which Reynolds did not appear was a 41-3 victory over Virginia Military Institute, a Football Championship Subdivision school.

“It’s just football,” Reynolds said. “At the end of the day it’s the same game we’ve been playing since I was five years old. You just have to go out there and focus. I love my teammates so much that I can’t let my selfish emotions get in the way.”