Philip Rivers in fine form during the Chargers’ 28-6 rout of the Cowboys

There was a little Decatur, Ala., on the field with Philip Rivers on Thursday.

That was the town where he grew up, fantasizing of playing in the NFL; where he obsessed over football with his father and grandfather, and where he doctored photos to include his face on the cover of Sports Illustrated.

It was one of the first things on his mind after he led his team to a 28-6 victory over the Dallas Cowboys.

“I think it’s moments and games like this, where I go, ‘This is what I dreamed of as a kid,’ ” Rivers said in the locker room. “You’re going to play the Dallas Cowboys on Thanksgiving at 35 years old. What in the world? Does it get any better?’ I think a little of that lets you just go, ‘Ahhhhhh.’ ”

The primal scream from Rivers came after his team completely dominated the Cowboys in front of a national audience, the score not fully representing the margin between the teams.

He had just played one of the best games of his career, throwing for 434 yards and three touchdowns with only six incompletions in 33 attempts.

It’s the fifth time he has thrown for more than 425 yards in a game, and the first time his team won when he’s put up those numbers.

Rivers threw for 219 yards in the first half, but the Chargers led only 3-0. After his first touchdown in the third quarter, a throw to Hunter Henry into a tight window in the end zone, Rivers shuffled his feet as if he was Muhammad Ali — though on the doorstep of 36 years old, he floats more like a buffalo than a butterfly.

On the next drive, he found receiver Tyrell Williams on the Dallas sideline for a 27-yard score, throwing the ball to the perfect spot for the connection to be made.

On his third touchdown, Rivers hit Keenan Allen, who skirted around five tacklers on the way to a 42-yard score.

It was a Thanksgiving carving that Rivers won’t forget.

“It was special,” he admitted.

Allen was electric for the second week in a row, catching 11 passes for a career-best 172 yards. Henry caught five passes for 76 yards and four other receivers caught passes for at least 16 yards.

“I just think we got into a groove,” Allen said. “We got into a rhythm and we just beat their defense. We ran better plays.”

The Chargers didn’t just beat the Dallas defense. They made life pretty miserable for the Cowboys’ offense too.

The Cowboys had their biggest play of the game, a 34-yard Dak Prescott scoring run, negated by a fairly obviously holding penalty on tackle Tyron Smith, the ex-USC star. The run, which came with the Chargers leading 9-0, was erased and, thanks to Joey Bosa, Prescott tossed a pass out of bounds and Dallas was forced to punt.

The Chargers’ defense later would intercept Prescott twice, with Desmond King nabbing the first pick of his career and returning it 90 yards for a touchdown. Casey Hayward also grabbed his third interception in the last two games as boos filled AT&T Stadium.

“They’re scoring with the football now on defense, and they’re taking the ball away,” Chargers coach Anthony Lynn said. “The turnovers have made a big difference.”

The defense was solid from the opening kick. The offense, though, ran into some early problems.

Kicker Nick Novak, who had been on the team’s injury report during the short week of practice, missed his first field goal and injured his back. Without a kicker available, the Chargers couldn’t settle for field goals … nor could they get in the end zone using four downs.

Novak gritted his teeth and made a 22-yard field goal on the team’s third trip into the red zone in the first half, giving the Chargers a 3-0 lead at the break.

“It’s frustrating to feel like you’re dominating the game and you’re up by three,” Lynn said. “We just stuck with the plan.”

Rivers and the Chargers marched down the field and scored on the first drive of the second half, and from there they were off.

With the win, the Chargers (5-6) have staked a serious claim at the final wild-card spot in the AFC, looking like the class of a group of contenders that includes Baltimore, Cincinnati, Buffalo, Miami, Houston, Oakland and the New York Jets. The Cowboys (5-6) lost their third in a row.

“It was an all-around team win — one we needed to keep us in the mix,” Rivers said. “We’ve still got a ways to go.”

And Rivers wants to be there for every part of a football journey that’s not quite over.

After reminiscing about his boyhood dreams, he shifted gears to acknowledge some adult insecurities. With his football team losing games, with his interceptions on the rise, he’d heard the whispers that maybe his tank was running out of gas.

Thursday, he said, was partly about that as well.

“I’d argue with some who’ve said I haven’t played as well the last couple of years. In some ways, I haven’t. In some ways I have. That might add to it too,” Rivers said with a grin. “This was a little bit of ‘Not so fast. …Hold on. Don’t try to run me off yet.’ ”

There’s still more dreaming to do.

dan.woike@latimes.com

Twitter: @DanWoikeSports