Game week is here. Months and months of anticipation becomes reality on Sunday in Las Vegas as No. 23-ranked USC takes on No. 13 LSU at Allegiant Stadium.

Kickoff is set for 4:30 p.m. PT on ABC.

It's Year 3 of the Lincoln Riley Era, Caleb Williams is now in the NFL and redshirt junior Miller Moss takes the reins at quarterback, and the defense has been almost entirely rebuilt with new coordinator D'Anton Lynn, his staff and a slew of transfer additions.

Storylines abound heading into his marquee season-opening matchup, and we could have made an endless list in that regard, but we'll focus here on our top five angles and subplots heading into Sunday.

Not only is the USC-LSU showdown the only college football game scheduled for Sunday, it's one of just three games on the opening week slate to feature two ranked teams.

The Trojans come into the season ranked No. 23 in the AP poll while LSU is No. 13.

The other marquee matchups with ranked teams this week are both Saturday, with No. 14 Clemson and No. 1 Georgia meeting in Atlanta and No. 7 Notre Dame playing at No. 20 Texas A&M.

Both Trojans coach Lincoln Riley and LSU coach Brian Kelly have suggested that such high-profile non-conference games could become rarer moving forward.

"I think if the playoff stays the way that it is right now, then I think you'll see less and less of those," Riley said. "Especially with us and the SEC, just because our schedules are already going to be so good, at some point you're like, all right, is the juice worth the squeeze, right, in terms of playing these games?

"As competitors, we all want to play these games. Now, if and when the playoff shifts again, if you start talking about if something were to happen -- let's say even more guaranteed spots in some of these conferences, then I think it could lend itself to these games being back and more prevalent. Which would be good for the game, because games like this are awesome."

Said Kelly: "The conference realignment had not occurred when this [matchup] unfolded, and then we were so far down the line in terms of getting this done, in terms of Las Vegas being involved and the financial considerations being involved. ... Moving forward, these may not be the kind of things that you see relative to openers. So again, I think we were too far down the line to want to make any changes with this opener. I think it's still an appealing opener even given the changes that have occurred."

Riley also opined that the College Football Playoff committee has to adjust the way it evaluates season resumes with the expanded 12-team playoff format and with the Big Ten and SEC becoming the two most loaded conferences.

"There's no question, losses -- no matter who they're to -- have outweighed everything else, and history has taught us that. Now that you have two super conferences -- or whatever you want to call these, you've got two conferences that are way out in front of everybody else right now, all right? -- there's going to have to be a shift in thinking. Like, there has to be, or it won't work," Riley said. "So how much value do they place on the ninth game? How much value do they place on playing Notre Dame vs. some directional school? It's going to have a big impact on how we all schedule in the future, so if they want these matchups then they need to value them accordingly."

USC is 1-1 all-time vs. LSU, winning 17-12 on the road in 1979 and losing 23-3 at home in 1984. This is the Trojans' first clash with a SEC foe since the 2016 season opener when they lost 52-6 to Alabama in a neutral site showdown.

These teams and programs sure do have a lot of similarities entering this season.

Riley and Kelly are both entering their third seasons at the helm after both stunned college football by leaving one marquee program (Oklahoma and Notre Dame, respectively) for another when they switched jobs, and both have some mounting pressure to deliver this season.

In Kelly's case, he's led LSU to back-to-back 10-win seasons, but the Tigers have finished outside of the top 10 in the final rankings both years. Just like Riley at USC, Kelly led LSU to the conference championship game in his first season (losing 50-30 to Georgia) but fell out of contention last year.

In Riley's case, the 8-5 finish last year has elevated scrutiny on the trajectory of what he's trying to build with the Trojans.

Due to defensive letdowns last season -- LSU finished ranked 105th in total defense (416.6 yards per game allowed) while USC was 116th (432.8 YPG) -- both programs changed out their defensive coordinators with the Trojans hiring D'Anton Lynn away from UCLA and the Tigers hiring Blake Baker from Missouri.

(LSU also has a new offensive coordinator as Mike Denbrock left for the same position at Notre Dame, with Kelly promoting QBs coach Joe Sloan to OC and play-caller.)

Both teams are also replacing a Heisman Trophy-winning quarterback -- Caleb Williams and Jayden Daniels -- with a fourth-year QB who has one career start on his respective resume.

Both USC's Miller Moss and LSU's Garrett Nussmeier made their first starts during bowl season last year and put up impressive stats. Moss, of course, passed for 372 yards, 6 touchdowns and 1 interception in a Holiday Bowl win over Louisville, while Nussmeier passed for 395 yards, 3 TDs and 1 INT in a win over Wisconsin in the ReliaQuest Bowl.

Both Moss and Nussmeier were four-star prospect in the 2021 recruiting class with Nussmeier ranked the No. 7 pro-style QB and Moss the No. 8 pro-style QB that year.

Furthermore, LSU and USC each lost their top two receivers as well. The Tigers are replacing Malik Nabers (89 catches for 1,569 yards and 14 TDs last season) and Brian Thomas Jr. (68-1,177-17) with redshirt senior Kyren Lacy (30-558-7) and redshirt junior Chris Hilton Jr. (13-225-2) the top returning wideouts. LSU also brought in Liberty transfer CJ Daniels (55-1,067-10). USC, of course, lost Tahj Washington (59-1,062-8) and Brenden Rice (45-791-12), with sophomores Zachariah Branch (31-320-2) and Duce Robinson (16-351-2) the top returning wideouts.