TUSCALOOSA, Ala. — We all should have seen this collision coming when the preseason polls were released. Alabama and Clemson have been the top two teams in the country all season, so the meeting of these two titans in the College Football Playoff national championship should surprise no one.

In the semifinals, Clemson smashed Notre Dame 30-3 and Alabama easily handled Oklahoma 45-34 in a game that wasn’t as close as the final score made it look.

This is the third time in four years these two programs are meeting for the national championship, and the fourth straight year they’ve played in the Playoff. They’ve clearly separated themselves from pretty much everyone else in the country. Some pundits and fans of other programs will tell you how they’re tired of this matchup, but ignore them. If you want the two best teams each year, then here they are.

We’re only a few days away from Monday’s showdown, so let’s get into the matchup.

Here are five things Alabama should be concerned about against Clemson.

Clemson’s defensive line

Clemson has an elite defensive line even without Dexter Lawrence, who has been ruled ineligible. No disrespect to LSU or Mississippi State, but this might be the best front Alabama’s offensive line has faced all year. Clemson is No. 1 in the nation with 52 sacks. Tua Tagovailoa’s ankle will certainly be tested if Alabama can’t protect him against Clemson’s vaunted front.

If Alabama’s offensive line can win this matchup, there’s no question Alabama wins this game.

Trevor Lawrence’s deep ball

The biggest difference in Clemson this year compared to last year is freshman quarterback Trevor Lawrence, who can stretch the field with deep passes. Lawrence connected on multiple deep shots for touchdowns in Clemson’s beatdown of Notre Dame.

Alabama’s secondary is better than the Fighting Irish’s, but the Crimson Tide will need its pass rushers to get after Lawrence. If Clemson’s offensive line can hold up against Alabama’s front and give Lawrence time, it will put the back of Alabama’s defense in a bind. Clemson’s receivers have shown they can win 50-50 jump balls.

Justyn Ross, Tee Higgins, Travis Etienne, Hunter Renfrow

Clemson has one of the best group of skill players Alabama has seen this season. Running back Travis Etienne leads the way on the ground. He has rushed for 1,572 yards and 22 touchdowns on the year, including 109 yards and a score against Notre Dame.

Receiver Tee Higgins didn’t put up huge numbers against the Irish, but he had one of the most acrobatic touchdown catches you’ll ever see, pinning the ball to his chest with one hand while dragging his feet as he fell out of bounds.

Ross exploded against Notre Dame, catching 6 passes for 148 yards and two long touchdowns. Ross manhandled the Irish’s secondary all afternoon. He’s a big, physical kid (6 feet 4, 210 pounds) that Alabama will have to watch closely.

Every Alabama fan remembers what Renfrow did in the 2015 and 2016 title games. Alabama held him in check last year in the semifinals, but that doesn’t mean he should be overlooked. Alabama’s secondary will have its hands full all night.

Revenge factor

There was a revenge factor for Alabama all last season after losing the 2016 national championship to Clemson. Well, the Tigers have similar motivation this year.

Alabama kind of embarrassed Clemson last year in the playoff. The score was 24-6, but it didn’t look that close. The Tigers and head coach Dabo Swinney will be fired up to take another championship from Nick Saban and Alabama.

Christian Miller’s health

Christian Miller has been one of Alabama’s top pass rushers this year. Miller’s 8.5 sacks ranks fifth in the SEC and second on the team. He had a sack on Oklahoma’s Kyler Murray in the Orange Bowl, but later left the game with a hamstring injury. The problem with hamstrings is that one small tweak can set a player back. The quick turnaround is going to make it tough on Miller to get back to 100 percent.

If he can’t go or is limited, Alabama’s pass rush takes a big hit.