There have been several adjustments to the structure of the 2020 college football season, from start dates to conference formats and more. But one matchup has been a mainstay: Clemson at Notre Dame. The Fighting Irish have a schedule against ACC opponents that extends more than a decade into the future, so this regular season meeting between 2018 College Football Playoff foes has long been circled as one of the biggest games of the year. 

There is just no way that anyone could have expected the circumstances surrounding it. 

No one could have guessed that a global pandemic would lead No. 4 Notre Dame to do the unthinkable and join the ACC as a full member, even if only for one season. No one could have guessed that a positive test for the coronavirus, not a physical injury sustained in a game or practice, would be the reason that star quarterback Trevor Lawrence will watch No. 1 Clemson play from his apartment.    

But what we could have guessed and would not have been surprised to find out if given a chance to look into the future is that Clemson and Notre Dame are two of the best teams in the country heading into November. The Tigers' run of dominance over the last five years has been repeated ad nauseam, but Notre Dame has become one of the most consistently strong programs in recent years and deserves its high ranking and reputation. The Fighting Irish are 39-6 dating back to the start of the 2017 season and 29-3 in their last 32 games, with double-digit wins every year. 

The top-five showdown, in which Clemson is a 5.5-point road favorite per William Hill Sportsbook, also helps Notre Dame make a mark in the ACC record books. Saturday night's showdown is just the sixth meeting between such opponents in league history. The good news for the Irish is the lower ranked team has won four of the five previous meetings, but none of them involved the No. 1 team in the country. 

That top-five status is only one small piece of the many fascinating angles to Saturday night's clash in South Bend, Indiana. Here are five more storylines, some on the field and some off, to track heading into the game.

1. Game will be decided in the trenches

As basic as it sounds, not every college football game is being decided by play at the line of scrimmage in 2020. Modern offenses continue to stress tempo, the run-pass option and quarterbacks keeping defenses on their toes with the quick pass game. But Notre Dame is that team that forces you to be elite at the point of the attack on both sides of the ball. It's built in to the identity that Kelly and his staff have forged in the weight room and on the field in the last three years that if you control the line of scrimmage, you control the game.  

Clemson will have its hands full with a Notre Dame offensive line that rates as one of the best in the country, led by two All-American candidates in left tackle Liam Eichenberg and center Jarrett Patterson. The entire starting five stands taller than 6-foot-4, weighs between 290 and 330 pounds and are upperclassmen. The strength, size, experience and execution is what makes them great and powers one of the top running games in the country. Clemson's efforts to stop the run are where the matchup hinges, with the Tigers hoping to force Notre Dame into third and longs and let Ian Book try to beat them over the top with the downfield passing attack. 

The same emphasis on line play is going to be the key to Clemson establishing some rhythm for freshman quarterback D.J. Uiagalelei. Boston College sold out to stop the run and Uiagalelei was able to answer the challenge with 342 yards on 30-of-41 passing and three total touchdowns (two passing, one rushing), but the Eagles do not have a player that compares to Notre Dame safety Kyle Hamilton or a back seven that has played as well as the Fighting Irish. Notre Dame doesn't have to blitz a lot because its front four does a good job of winning their battles against the offensive line, which leaves the linebackers and defensive backs to mix and match coverages and swarm to the ball in the open field. Just like Clemson, Notre Dame's goal is to stop the run on first and second down and force the freshman quarterback to beat them down the field in third and long scenarios.   

2. Uiagalelei's showcase opportunity

Uiagalelei passed the test of beating Boston College with the help of Clemson's veterans. Senior wide receiver Cornell Powell, senior wide receiver Amari Rodgers and senior running back Travis Etienne -- who is well on his way to becoming the most decorated player in ACC football history after setting the career rushing record against Boston College -- were challenged to step up and help the freshman quarterback in his first start. The use of Etienne, in particular, stands out as a key not just against that rock solid Notre Dame defense. but all season. When Clemson's offense gets caught in a tricky down and distance, the answer remains to give the ball to No. 9 and let him go to work. The vision, acceleration and strength to break tackles has made Etienne one of college football's superstars over the past three years and it's the biggest key to making Uiagalelei's life easier against the Irish. 

That said, there is also Uiagalelei's potential that could be realized on this huge stage. As a five-star prospect, he is projected to be a first-round NFL Draft pick at the end of his college career and industry experts have dubbed him the next quarterback in line to add a national championship to Clemson's trophy case. Offensive coordinator Tony Elliott certainly knows the potential is there and feels good after seeing him throw for nearly 350 yards on 73% passing with no turnovers. So good in fact he was drawing comparisons to Lawrence, Deshaun Watson and Patrick Mahomes after the win. 

"Like Watson with that quiet confidence. Never rattled, ice water in his veins," Elliott said. "A little Mahomes in him 'cause he can make throws off his back foot, off-balance, can change arm angles. Rifle arm like Trevor. The more we put on his plate, he's never been overwhelmed."

No pressure, right? Just getting compared to three of the best quarterbacks in all of football after your first career start. Elliott is clearly excited about the ceiling of Uiagalelei and the Tigers offense with him leading the charge in the future, but it will be fascinating to see what the next steps might be in the present on Saturday night against a veteran-led Notre Dame defense.   

3. Brian Kelly tired of hearing about the 'gap'

The Notre Dame coach had some spice this week leading up to the game, making it seem like he's really tired of hearing about how the 2018 loss to Clemson in the College Football Playoff exposed some kind of gap between the Irish and the elite teams in college football. "The they went and blitzed Alabama," Kelly said of the 2018 Tigers, "and I didn't hear anyone saying anything about the talent gap or the coaching gap there." 

Kelly had his talking points down -- "we're 29-3 over our last 32 games" and "we've won 12 in a row" -- as the refrain when the media posed questions about whether Notre Dame looks at Saturday night's game as a chance to level up as a program or what has changed since that 2018 loss. He believes that Notre Dame is at the elite level already, and frankly he doesn't know what else the program has to do to make that clearer to the pundits across the country. Kelly did note the difference in raw talent with these two rosters, somewhat joking (but not joking) that he'd gladly take Clemson's third and fourth string players but explained that these are two programs that go about their business in different ways. He believes in the way Notre Dame has committed to building a program, and he seems to take issue with the idea that it's not good enough to compete against the best teams in the country. 

4. Clemson on greatest run in ACC history? 

With a win on Saturday night in South Bend, Clemson would move into a tie for first place in ACC history with 29 consecutive wins against league opponents. That record was set and has been held by Bobby Bowden's Florida State program that ran off more than three seasons of wins against ACC foes immediately upon joining the league from 1992-95. Bowden's Florida State run of top-five finishes from 1987-2000, with two national championships (1993, 1999) in that span, is long considered one of the best in college football's 150-plus year history. The ACC portion of that run included nine straight conference titles, a mark that Clemson is still a few years short of matching. 

But as Clemson has a chance to tie the consecutive wins record, it's worth starting the conversation as to whether these Tigers are on the most impressive run in league history. The ACC is more difficult to win in the College Football Playoff era than it was in the 1990s thanks to conference expansion and the addition of the ACC Championship Game. Additionally, Clemson has already matched the number of national championships won by those Florida State teams (two) in the 1992-2000 run in a tougher era with an added game in the College Football Playoff.

The relentlessness of how Clemson works its way through league foes matches the experience for those who faced Florida State in its prime. The celebration that occurs when the juggernaut falls, which last happened to Clemson at Syracuse in 2017, is the kind of moment that a program holds onto for years. Clemson's run has no expiration date so it's possible that while the Tigers current run may already be more impressive than FSU's, they might outright surpass those numbers.

5. College Football Playoff implications 

I take great issue with the talking point that Saturday night's result "doesn't matter" because Lawrence is not on the field for the Tigers. The CFP Selection Committee does take "player availability" into consideration for its deliberations when ranking the best teams in the country, so regardless of result, it is true that Lawrence's absence will be a qualifier, but the result carries massive implications for both teams. If Notre Dame wins, it takes the inside track to play for the ACC Championship in Charlotte. Even in the event of a loss to the Tigers in the rematch, the Irish could have a one-loss profile that would certainly warrant playoff consideration. 

If Clemson wins without Lawrence, the credit gets passed to the entire team as validation of the Tigers' position as the No. 1 team in the country. If the Tigers were to stumble down the stretch or lose to Notre Dame in the ACC Championship Game, then a win without Lawrence can be used as this tangential tiebreaker when splitting hairs between the teams in the top five. So the conversation is not that the game "doesn't matter" for the College Football Playoff race. it matters immensely, we just don't know how yet.