JACKSONVILLE, Fla. -- The Los Angeles Rams' defense spent an entire week preparing to stop the Jacksonville Jaguars' rushing attack, then watched it all blow up on them in a matter of 11 seconds.

Leonard Fournette, coming off a 181-yard game against the Pittsburgh Steelers, broke a 75-yard touchdown run on his team's first offensive snap. The 228-pound rookie found a wide-open hole in the "A" gap, brushed aside a feeble tackling attempt by inside linebacker Mark Barron and exploded into the second level, beating rookie safety John Johnson up the field and spoiling any joy the Rams might have felt from watching Pharoh Cooper turn the opening kickoff into six points.

"I'm sure somebody got out of their gap or something," Barron said. "That's the only way those type of plays happen."

Walking back to the sideline, Barron remembered something that first-year head coach Sean McVay says often: "Don't flinch."

Later, Alec Ogletree, an inside linebacker and a captain, strolled up and down the bench and reminded his teammates that an entire 60-minute game remained. Connor Barwin, an outside linebacker in his ninth season, had a similar message.

"'That play's over,'" Barwin said. "'Don't let that play dictate our mood the rest of the game. It's one play. Move on to the next play.' That was the message. That's the way we played."

The Rams eventually overcame that play, winning by a 27-17 score on Sunday, in a game dominated by their special teams and their defense. Fournette gained 98 yards on his first four carries, but only 32 yards on his next 17. The Jaguars scored 14 points on 159 yards in their first three drives, but only three points on 230 yards in their next 13.

By the end of Week 6, Fournette's opening run was a distant memory.

Aaron Donald recorded a sack and three hits on Jaguars quarterback Blake Bortles. Sam Greenwood/Getty Images

"It's a long game," defensive tackle Aaron Donald said, his team 4-2 and in first place in the NFC West. "If you let that hurt you and keep thinking about that, it'll be an even longer game."

The Rams' defense turned it around in Jacksonville the way it has over these past three weeks. Wade Phillips' unit gave up 90 points in a 10-quarter stretch against the Washington Redskins, San Francisco 49ers and Dallas Cowboys from Weeks 2 to 4. In the 10 quarters that followed -- dating back to the second half in Dallas -- the Rams have allowed only 39 points.

"They continue to improve," McVay said.

"I think we're in a decent place," Barron said, "but I think we'll keep getting better."

A big reason for their surge, as McVay pointed out, is the dominance exhibited by Donald, who picked up his second sack on Sunday and is consistently penetrating into the backfield. Another reason is a couple of key adjustments by Phillips, who moved Michael Brockers to defensive end and carved out a path for rookie safety John Johnson. But the Rams have also benefited from more time in this system.

Early on Sunday, they missed a handful of open-field tackles and apparently had a hard time setting an edge. But then, once again, the Rams resembled the elite defense they expected to be.

"From day one, I knew we could be a top defense," Ogletree said. "It's a matter of everybody getting the system down and keep playing, each and every week, and just getting better in practice. I feel like we've been doing that lately, and it's starting to show."