Keenan Reynolds (No. 19 ) and Navy passed for 158 yards while their prolific rushing attack was held to 134 yards. (John McDonnell/The Washington Post)

The Navy football team’s normally productive triple-option offense didn’t get started in earnest until the fourth quarter Saturday. Fortunately for the Midshipmen, its defense was unrelenting for virtually the entire game during a 31-14 win against heavy underdog Tulane on an overcast afternoon at Navy-Marine Corps Memorial Stadium.

That unit forced three consecutive turnovers in the second half and produced a critical stop with the Green Wave two yards from the end zone. Quarterback Keenan Reynolds, meanwhile, ran for a pair of touchdowns, including a one-yarder for a 17-point buffer, to move within two rushing touchdowns of the career record (77) for major-college football players.

Reynolds all but sealed the outcome on his second touchdown with 3 minutes 38 seconds left in the game on the possession following teammate Lorentez Barbour’s interception. The senior safety made a sliding catch on quarterback Tanner Lee’s throw over the middle, and the Midshipmen got the ball at the Tulane 36-yard line with 8:33 to play in front of an appreciative homecoming crowd of 32,033.

“A win’s a win, Dog,” Navy Coach Ken Niumatalolo said, recounting a conversation between teammates he overheard while walking into the locker room. “That’s the approach I’m taking. We knew they were going to be tough interior-wise defensively. We saw that coming. They played really good defensively, had a really good plan. We knew it was going to be tough sledding.”

Navy (5-1, 3-0) remained one of three unbeaten teams in the American Athletic Conference West Division, along with No. 18 Memphis and No 21 Houston, in its first triumph with more passing yards (158) than rushing (133) since a 31-17 win against Army in 2010. Reynolds led the Midshipmen in rushing with 38 yards on 23 carries, ending a career-best four games in a row with at least 100 yards.

Among the most important sequences unfolded with Tulane (2-5, 1-3), trailing by 10, at the Navy 2 early in the fourth quarter. On third and one, Lee tried a sneak, but linebacker Daniel Gonzales popped the ball loose with his helmet, and defensive end Will Anthony recovered at the 1. It was the first forced fumble of Gonzales’s career and Anthony’s fifth recovery.

“During halftime we had a good talking-to,” Anthony said. “It was a real punch in the throat for me. It was a reality check, like we need to turn this game up. Second half, it took us a while to get ourselves rolling, but definitely we had some guys on the sideline making sure we turned it up out there.”

The only points of the third quarter came courtesy of fullback Quentin Ezell’s nine-yard run through a hole on the left side to extend the lead to 17-7. The senior’s fifth touchdown of the season concluded a seven-play series over 66 yards and lasting 3:02. The Midshipmen converted two third downs during the possession, including wide receiver Thomas Wilson’s nine-yard catch on third and seven.

The scoring drive came following a change of possession on downs when Navy linebacker Micah Thomas stopped tailback Dontrell Hilliard for no gain on fourth and one. The Midshipmen took over at their 34-yard line with 8:25 to play in the third quarter.

After Tulane tied the score at 7 with a 19-yard touchdown run from Hilliard early in the second quarter, the Midshipmen settled for Austin Grebe’s 25-yard field goal to reclaim the lead. Navy had reached the 3-yard line facing first and goal, but Reynolds lost one yard, and on third down, fullback Shawn White was dropped for a five-yard loss to the 8.

Tulane narrowly missed a chance to take the lead in the closing seconds of the first half. Lee lofted a pass into the left corner of the end zone, and wide receiver Devon Breaux attempted a diving reception, but the ball came loose as he was going to the ground. Breaux was wide open after running past senior cornerback Quincy Adams.

A holding call pushed the Green Wave back to the 31, and the first half ended with place kicker Trevor Simms missing a 49-yard field goal attempt that landed right and well short.

“We made the adjustment. We knew we had to throw the football to move the football,” said Reynolds (7-for-11 passing, 134 yards, no interceptions), who started after hurting his leg in a 41-24 loss to Notre Dame two weeks ago but was able to rest during a bye. “We practice it all the time, so it wasn’t like it was a completely new deal.”