Wade Phillips stood on the sideline at AT&T Stadium, his play card in his left hand, his right hand on his hip.
The Rams defensive coordinator watched as quarterback Dak Prescott lined up the Dallas Cowboys inside Rams' territory, facing fourth and 10 with 36 seconds left.
Prescott completed a short pass to Ezekiel Elliott, who turned to run as linebacker Connor Barwin dragged him down.
Rams players signaled Elliott short of a first down. Phillips looked around, waiting for confirmation.
Officials measured, and the chains proved Barwin made the tackle with less than a yard to spare.
Phillips' defense finished the job in the 35-30 comeback victory, which marked Phillips' first appearance against his former team since he was fired as head coach in 2010.
"Guys made plays when they needed to," linebacker Robert Quinn said after the game. "And we made plays at the end to seal the deal."
The Rams (3-1) are in first place in the NFC West and return home next week to face the Seattle Seahawks.
Coach Sean McVay presented Phillips with a game ball after the victory as players surrounded their 70-year-old coordinator and ruffled their hands through his hair.
"I can't say enough about the defensive effort," McVay said.
The Rams struggled against the run the last two weeks. Even Phillips made an unprompted jab about his unit's need to fix the issue during a weekly news conference.
The secondary and pass defense, through three weeks, appeared solid.
But in the first half against the Cowboys, every aspect of Phillips' 3-4 scheme appeared broken.
Phillips started rookie Tanzel Smart in place of Ethan Westbrooks in an attempt to slow the run. The change didn't initially help.
In the first half, Prescott passed for 155 yards and two touchdowns, Elliott rushed for 56 yards and backup running back Alfred Morris broke off a 70-yard run.
And three-time Pro Bowl receiver Dez Bryant caught two passes for 50 yards against franchise cornerback Trumaine Johnson.
"They were making plays," Quinn said, "keeping us on our heels."
Said Johnson: "We made a couple mistakes."
Phillips huddled with the defense at halftime, and Alec Ogletree delivered an impassioned speech, according to safety Maurice Alexander.
After allowing the Cowboys to score in each of their four first-half possessions, the Rams made four consecutive stops, followed by an interception.
"Guys stood up," McVay said. "And they were much more efficient on early downs."
Prescott struggled to find a rhythm as the defense brought pressure.
"They had a solid rush," Prescott said.
Lineman Michael Brockers forced Prescott to make an errant pass that linebacker Mark Barron intercepted. The turnover was converted into a field goal that gave the Rams a 32-24 lead.
"We locked in and came out and played better," Barron said. "We weren't satisfied with the first half. Just came in and tried to reset everything."
Barwin and Brockers each sacked Prescott. Lineman Aaron Donald recorded two quarterback hits and a tackle for a loss.
Prescott completed 20 of 36 passes for 252 yards and three touchdowns. Elliott rushed for 85 yards — only 29 in the second half .
"I'm glad how we bounced back," Johnson said. "All those plays were fixable."