First look at Alabama-Oklahoma and Clemson-Notre Dame

Kelly: 'We know who we're gonna play' (3:39)

Notre Dame head coach Brian Kelly says his team is excited for the opportunity to play Clemson in the College Football Playoff semifinals. (3:39)

The matchups for the College Football Playoff are finally set. Here's an early preview of what to expect when Alabama faces Oklahoma and Notre Dame squares off against Clemson.

College Football Playoff Semifinal at the Capital One Orange Bowl
Hard Rock Stadium, Miami Gardens, Florida
Dec. 29, 4 p.m. or 8 p.m. (ESPN & ESPN App)

No. 1 Alabama vs. No. 4 Oklahoma

Two of college football's most storied programs. A dream quarterback matchup, pitting the two Heisman front-runners against each other. The nation's top two offenses squaring off.

Oklahoma taking on Alabama figures to be one of the most compelling semifinal showdowns of the playoff era.

The defending national champion Crimson Tide will be the heavy favorites after winning every game during the regular season by at least 22 points before rallying past Georgia in the SEC championship game in dramatic fashion.

While the Crimson Tide have been dominant on both sides of the ball yet again, they've been a different monster offensively than past seasons because of quarterback Tua Tagovailoa. In his first season as the full-time starter, Tagovailoa passed for 37 touchdowns with only four interceptions. And even though he struggled in the SEC championship before leaving with an injury, Tagovailoa could very well become Alabama's third Heisman Trophy winner.

If Tagovailoa doesn't win the award, the Sooners' Kyler Murray will. And if there's an offense that's even more lethal than Alabama's this season, it's Oklahoma's.

Quarterbacking an attack that is averaging almost 50 points per game, Murray has already broken Baker Mayfield's school record for total offense. Following Mayfield, he could give the Sooners back-to-back Heisman winners, as well.

Yet as electric as the quarterbacks have been, defense is what distinguishes these two squads. And that's where Alabama owns a massive advantage. The Crimson Tide rank No. 2 nationally in defensive efficiency; the Sooners are 91st.

That said, Oklahoma's defense has come up with a few big plays of late. It'll have to come up with a whole lot more if the Sooners stand any chance of pulling off the upset.

Key player for Alabama: Mack Wilson is going to have to play his best game to stop the potent Oklahoma offense. And we're not just talking about what he'll have to do when shadowing the fleet-footed Murray, who is almost impossible to contain. As the Mike linebacker and signal-caller of the defense, Wilson will have his hands full watching Murray and keeping the rest of the defense on task. Anything out of place, any check he leaves uncalled, could spell trouble against the Sooners.

Key player for Oklahoma: The Sooners are going to need Murray's very best to topple Alabama. Because of his prolific ability to pass and run, Murray has the skill set to give Alabama problems. If he can put the Crimson Tide on their heels with big plays, Oklahoma could be in business.

Most important matchup: Alabama's imposing wide receivers against Oklahoma's diminutive defensive backs. The Crimson Tide feature a talented receiving corps, headlined by Biletnikoff Award finalist Jerry Jeudy. OU's smallish secondary has been picked on by physical wide receivers all year. If that happens against the Crimson Tide, the Sooners could be in for a long day.

X factor: Might the hook for Tagovailoa be shorter this time around? His once-golden arm lost some shine against Georgia when he threw two interceptions and exited the game with the Tide trailing in the fourth quarter. That he suffered two different leg injuries, including aggravating a knee issue that has plagued him all season, is also cause for concern. Jalen Hurts certainly played well off the bench and showed that he's still the quarterback who went 26-2 as a starter and won SEC Offensive Player of the Year. But by doing so, and proving he can still beat elite defenses, Hurts might have given coach Nick Saban something else to think about when he considers how to handle Tagovailoa should he get off to another rocky start. -- Alex Scarborough and Jake Trotter

Goodyear Cotton Bowl Classic
AT&T Stadium, Arlington, Texas
Dec. 29, 4 p.m. or 8 p.m. (ESPN & ESPN App)

No. 2 Clemson vs. No. 3 Notre Dame

The last time these two teams met in 2015, Clemson coach Dabo Swinney brought his own guts, Mother Nature brought torrential downpours and the Fighting Irish brought the eventual national runner-up to the brink of an upending home loss before falling just short on a failed two-point conversion in the final seconds.

The college football universe would love a rematch with that kind of drama. This time the stakes are even higher with two undefeated teams battling for a spot in the national championship game.

This is getting to be routine for Swinney's team, which is making its fourth consecutive appearance in the College Football Playoff. The tried-and-true formula of a fearsome defensive front and electric playmakers on offense is complemented this year by star freshman quarterback Trevor Lawrence, who threw a pair of touchdown passes in a blowout win Saturday night that clinched the ACC title.

Notre Dame hasn't sniffed a title shot since 2012, when Brian Kelly juggled a pair of quarterbacks through an undefeated regular season on the path from South Bend to South Beach. That didn't go so well for the Irish, who have upgraded their athleticism since Alabama firmly put them in their place to claim the national championship that year.

Has Kelly's team come far enough in the six years since to fully close the gap between a program that was once the standard bearer of college football greatness and a Clemson team that has been neck-and-neck with the Crimson Tide in carrying that torch for the past several years?

A path to the playoff that turned out to be less challenging than expected provides room to doubt that Notre Dame belongs in the same conversation. Clemson had its own close calls before blowing through a weak ACC this year. Both teams get a chance to prove they're worthy in a game that will once again require all participants to bring their own guts.

Key player for Clemson: It's probably not a coincidence that Clemson's most problematic defensive performance this season (a 56-35 win over South Carolina on Nov. 24) came without Tre Lamar on the field. The junior linebacker isn't the biggest name on the Tigers' defense, playing second fiddle to the superstars on the line, but he might be the unit's most essential player. He's a Butkus Award finalist, and he does a little of everything for the Tigers' D, making him a critical piece of the puzzle, particularly against Notre Dame. Need to disrupt QB Ian Book's short passing game? Lamar is key. Have to stop Williams and the ground game? Lamar is key. He won't be the talking point during the month leading up to the game, but he'll be the glue for a unit that's already one of the best in the nation.

Key player for Notre Dame: Dexter Williams ran for 941 yards despite missing the first four games of the season. Against one of the four defenses in the nation that has allowed fewer than 100 rushing yards per game, Williams will need to make the most of the small creases and infrequent windows that he can find. Williams has given the Irish coaching staff all it could have expected and more since joining the lineup in late September, but he'll need to be at his best if Notre Dame is going to hang with Clemson.

Key matchup: Trevor Lawrence vs. Notre Dame's pass defense. Lawrence emerged as Clemson's starter in late September after several weeks of splitting time with Kelly Bryant under center. He has yet to face a secondary with the talent and depth Notre Dame brings to the table during an exemplary rookie season. Then again, All-America candidate Julian Love, safety Alohi Gilman and a host of other playmaking threats on the back end of Notre Dame's defense haven't had to lock down a group of receivers that could match up with the options Lawrence has at his disposal. Lawrence has thrown only four interceptions all season, none of them in his past three games. If he has a mistake-free game again, Clemson should have a great chance to return to its third championship game in the past four years.

X factor: Is it too much of a cliche to suggest experience is the difference here? For as talented as Notre Dame's roster is, this is uncharted territory. For Clemson, this is the starting point. The second Christian Wilkins, Austin Bryant and Clelin Ferrell announced they'd return for a final run, the expectation became a playoff berth, and the past three seasons -- a near miss, a national championship, a brutal ending -- have all been the foundation upon which the 2018 campaign was built. That's not to suggest the stage will be too big for Book or Drue Tranquill or Jerry Tillery, and it's true that Lawrence, the man leading the Clemson offense, is new to this as well. But it's still notable that in terms of expectations for Notre Dame, the playoff bid is the end of a long road in 2018. For Clemson, this marks the start. -- David M. Hale and Dan Murphy