The last time Alabama and Notre Dame played each other, it was a BCS championship blowout won by the Crimson Tide.
The last time Clemson and Ohio State faced off — just last year — they played one of the best semifinals in the College Football Playoff's 6-year history.
According to the oddsmakers, this season's CFP semis figure to be more of the same.
Alabama is about a three-touchdown favorite against Notre Dame when they play Jan. 1 at AT&T Stadium in Arlington, Texas, to open the semifinal doubleheader.
Clemson is favored by seven to beat Ohio State in the nightcap at the Superdome in New Orleans.
With help from ESPN analyst Greg McElroy and the SEC Network's Cole Cubelic, here's a look at some of the key matchups that could decide which teams play for the national championship on Jan. 11 in South Florida.
Alabama vs. Notre Dame
Let's be clear: The difference is in the dudes. The Tide simply have more elite players and dynamic athletes than the Irish.
Notre Dame coach Brian Kelly believes the talent gap has shrunk since the Irish lost 42-14 to Alabama in the 2013 BCS championship game. He is right. But is it enough to dramatically change the outcome eight years later?
A way to bridge the chasm could start with Notre Dame's tight ends.
Freshman Michael Mayer is likely a future first-round draft pick and Tommy Tremble is a versatile athlete who lines up at several positions. The Irish will also use three tight ends at times.
It's not so much that the tight ends can dominate the game with their pass-catching and playmaking. Cubelic said Notre Dame can use them in varying formations and motions to make it difficult for Alabama to identify who is doing what.
“The way you’re going to have success against (the Tide) is basically to not sit still and to get them to line up incorrectly,” said Cubelic, who played offensive line at Auburn.
The Irish offensive line is excellent and should hold up just fine against Alabama's defensive front, which could give Notre Dame the opportunity to run the ball, milk some clock, let quarterback Ian Book make plays with his legs and limit total possessions.
That's important, because on the other side of the ball, nobody is slamming the brakes on Mac Jones, DeVonta Smith, Najee Harris and a Tide offense that averages almost 8 yards per play.
The Irish need to find a few stops to have a chance. Cubelic and McElroy disagree on the best way to go about getting them.
Cubelic said Notre Dame should take Arkansas' approach, drop seven or eight into coverage, focus on taking away the deep throws and force the Tide to be patient. Of course, the Razorbacks lost 52-3, but Jones averaged only 8.7 yards per pass. On the season, he was up over 11.
McElroy said Notre Dame defensive coordinator Clark Lea should throw every pressure he has at Alabama.
“I think the best way for them to neutralize the throw game is to overload pressure and force the ball out of Mac Jones' hand earlier than he would like it to be forced out,” said McElroy, a former Alabama quarterback.
The Tide might be more susceptible to protection problems in their first full game without center Landon Dickerson, who was lost in the Florida game to a knee injury.
“I think that’s a massive, massive loss,” Cubelic said.
Clemson vs. Ohio State
Clemson beat Ohio State 29-23 in last season's semifinal, a game decided in the final minute.
These Buckeyes don't have a pass rusher like Chase Young or a shutdown cornerback like Jeffrey Okudah. Those top-three draft picks allowed Ohio State to play mostly man-to-man coverage last year.
McElroy said Ohio State is not as man-to-man reliant this season. So how the Buckeyes go about generating pressure on Trevor Lawrence and what solutions Clemson has could determine the rematch.
Ohio State's best defensive linemen are on the interior this year with Tommy Togiai and Haskell Garrett. On the other side, Clemson's offensive line has fallen off from last season.
“They're not playing well down the stretch,” Cubelic said.
Before wide receiver Cornell Powell emerged in the second half of the season for Clemson, tight end Braden Galloway was the Tigers' steadiest receiver behind star Amari Rodgers. This could be a game for Galloway.
“I think he is just waiting to explode,” Cubelic said. “I think Clemson offers some matchups that are going to be problematic because I think Ohio State is going to have to bring more than four to get to Trevor Lawrence.”
Ohio State's Justin Fields is the other future first-round NFL draft pick at quarterback in this game. He is coming off the worst performance of his college career in the Big Ten championship. Playing without star receiver Chris Olave surely didn't help, though the junior is expected back for the semifinal.
Trey Sermon and the running game carried the Buckeyes to a Big Ten title and playoff spot. McElroy and Cubelic agreed that is the path for Ohio State to snap a four-game bowl losing streak against Clemson.
“That run game has got to go for them and that's going to include the quarterback,” Cubelic said.
McElroy said the Buckeyes get pass happy instead of leaning on a talented offensive line led by guard Wyatt Davis and center Josh Myers.
“When they're just in standard zone-read, they're a problem,” he said.
McElroy said he thinks Fields and the Buckeyes have played tight through a lot of this season, maybe brought on by the Big Ten's late start, playing so few games and having no room for error.
He wouldn't be surprised if the playoff brings out the best in Fields and Ohio State.
“This is the first game this year where they will not have one iota of concern or worry," McElroy said. “Just go out there and let it rip.”
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