COSTA MESA, Calif. -- Los Angeles Chargers quarterback Justin Herbert is about to play the biggest game of his young NFL career. Beat the Las Vegas Raiders on Sunday night at Allegiant Stadium (8:20 p.m. ET, NBC) and the Chargers make the playoffs for the first time since 2018. Lose and it's back to, well, there's always next season.

Herbert will never say it -- he's too humble and unassuming -- but he knows the stakes and there's no doubt he's excited, which is different than being nervous. He's been through the nerves before -- in sixth grade trying to make the travel team, engineering a come-from-behind victory over Wisconsin in the 2020 Rose Bowl in college at Oregon and being thrown into the starting lineup minutes before the second game of his NFL career last year after Tyrod Taylor was injured.

But Herbert has had great coaches, great builders of the brick wall that has given him a structure to stand on, win or lose. Those who know him well say he's still more than excited every day (and somewhat in disbelief) that he gets to go out and throw to receivers Keenan Allen and Mike Williams, hand off to running back Austin Ekeler, stand across from defensive end Joey Bosa and try to figure out what safety Derwin James Jr. is up to.

"Fridays at 3 p.m. when the rest of our facility is empty, he and me are the last ones here," Chargers coach Brandon Staley said. "That never ceases to amaze me. That peace and quiet, that serenity in a pro building where you're kind of at the end of the week, your quarterback is still here. That never ceases to amaze me, but it does in the same way. It's a reminder of why he's earning all that he's earning."

And why Herbert is in the situation he's in.

There are two teams playing Sunday night with a chance to advance into the playoffs, and Herbert's Chargers squad (9-7) is one of them. That's pretty cool for a 23-year-old in his second season in the NFL. Staley realizes that, too.

"I've been in a lot of games like this in my lifetime, not in the NFL as a head coach, but I think that any time you're in a matchup like this where there's a lot at stake, it goes down to your preparation and you trusting in your game and treating that week like it has a life of its own," Staley said. "You have to pour into this week, have to pour into your team and make sure that you have the level of focus, the level of detail that the week requires.

"That's what we're trying to do; establish that consistency and performance during the week. I like the way that we've kind of gotten off to that start as a team, with me in my first year. I think we're always improving. We're going to need to this week."

James and other teammates are still surprised Herbert set the franchise single-season record for passing touchdowns last week, throwing his 35th of the season in a 34-13 victory over the Denver Broncos to break a record Philip Rivers set in 2008, and celebrated by tackling Williams, who caught the 45-yard touchdown pass.

"I don't like the guys tackling each other out there," James said. "But it was amazing seeing their celebration and the team's camaraderie together, everybody bonding for that special moment."

During the celebration, Herbert tried to hide from the camera that was stalking his every move. He didn't want the attention.

"Justin Herbert is a superstar," James said of his quarterback, who is 369 yards short of passing for 5,000 yards this season. "If you were to be around him, he's so humble. He doesn't like the spotlight. You have nothing but respect for a guy like that."

Herbert will have a chance to earn even more national respect on Sunday against the Raiders (9-7), who have won three straight to set up the showdown. The Chargers beat the Raiders in their first meeting, a 28-14 victory in Week 4 at SoFi Stadium.

What do Herbert and Staley talk about those Friday afternoons, when the sun is starting to set and the week of preparation is winding down?

"I normally head into the quarterback room before I leave," Staley said. "Knowing he's there, just to connect before the weekend, the calm before the storm. When you're towards the end of the week, you're trying to get into that space of how it's all of the preparation and now you're getting into the space of how it's time to go perform. It's one of those spaces during the week that I've enjoyed. At the same time, it's one of those reminders of what makes him really special."

Just don't ask Herbert about it.