As he walked out of the Coliseum tunnel to the field on Sunday, a buttoned-up Sean McVay stopped and greeted his father. He hugged his mother. He accepted well wishes from other family members and friends.
The 31-year-old McVay smiled but his expression belied a steely focus: He was about to make his NFL coaching debut.
A few hours later, after the Rams’ possibly game-changing 46-9 victory over the Indianapolis Colts, the youngest coach in modern NFL history headed back up the tunnel, his shirt untucked, his pants soaked from a sideline Gatorade bath.
Wearing the same determined smile, he pumped a fist at delirious Rams fans unaccustomed to the entertaining win they had just witnessed.
“It’s a little surreal,” McVay said of his first victory, “but it’s one game.”
It is only one game in a 16-game schedule, and it was achieved against a Colts team playing without star quarterback Andrew Luck and with a defense that featured 11 new starters.
But this looked nothing like the NFL’s worst offense last season.
Quarterback Jared Goff passed for 306 yards and a touchdown in his first NFL win. New receivers Sammy Watkins, Robert Woods and rookie Cooper Kupp made big plays. And running back Todd Gurley demonstrated that he can be a threat as a receiver as well as a runner.
The defense also produced game-turning plays.
Cornerback Trumaine Johnson and safety Lamarcus Joyner returned interceptions for touchdowns as defensive coordinator Wade Phillips’ 3-4 scheme shut down the Colts.
In just one game, the Rams scored more than half of the 89 points they produced in seven home games last season.
“That’s just a team effort — kind of what McVay started to preach here from Day 1,” veteran linebacker Robert Quinn said. “It’s just the first true game we get to show what we’re about.”
It figures to get more difficult next week against the Washington Redskins, McVay’s former employer.
As the Redskins’ offensive coordinator, McVay helped develop Kirk Cousins into one of the NFL’s premier passers. He has shown early signs of doing the same with Goff, the No. 1 pick in the 2016 draft.
“It’s a new offense and Sean has had the success he’s had in the past not by accident,” Goff said.
Goff completed 21 of 29 passes, without an interception, as the Rams amassed 373 yards against the Colts.
“He’s a No. 1 overall pick for a reason,” Colts coach Chuck Pagano said. “He’s a damn good football player and he did a great job as far as scheming what we were doing.”
Goff tossed an 18-yard touchdown pass to Kupp, one of eight receivers who caught passes from the 22-year-old quarterback. Operating behind a rebuilt line anchored by left tackle Andrew Whitworth, he took only one sack.
“He did a great job making good decisions,” McVay said.
Gurley rushed for 40 yards in 19 carries and also caught five passes for 56 yards. His five-yard touchdown run in the second quarter gave the Rams a 17-3 lead and started a run of 27 unanswered points.
“We scored some points on offense, trying to compete out there with the defense, man,” Gurley said.
The defense indeed dominated — the Colts were 0 for 10 on third down and completed only 11 passes — without lineman Aaron Donald, the three-time Pro Bowl selection who ended a holdout Saturday.
Donald did not attend the game but is expected to practice this week.
“We’ll figure that situation out as we move forward,” McVay said. “But, don’t want to take away from the great defensive effort it was for the guys that did play.”
The game also marked the first time that linebacker Robert Quinn and Mark Barron and cornerback Kayvon Webster played in a game with the other starters. The three players sat out the entire preseason so they would be physically sound for the opener.
They appeared to meld seamlessly.
“I was a little, I don’t know, skeptical,” Brockers said. “We didn’t really play in the preseason.
“Definitely, you want to get out there and knock the rust off. But to go out there and just dominate and execute all the calls that we had, I thought we did a good job.”
Johnson started the defense’s big day when he picked off Scott Tolzien’s first pass and returned it 39 yards for a touchdown.
Johnson was disappointed that the Rams did not offer him a long-term contract. He is playing under the franchise tag for the second consecutive season, and last week teammates voted him a team captain.
The leadership he displayed during the preseason continued Sunday.
“Just trying to set the tone early coming in on defense, and we did that,” said Johnson, who also forced and recovered a fumble.
Johnson’s touchdown put the Rams on track for a 27-3 halftime lead.
Greg Zuerlein’s third field goal increased the margin in the third quarter and Joyner consolidated the rout by picking off another Tolzien pass and dashing 29 yards to the end zone to make it 37-3.
“We have a whole new character around this team,” Brockers said, adding that the Rams don’t care about having the NFL’s youngest coach.
“All we care about,” he said, “is winning games.”
Follow Gary Klein on Twitter @latimesklein