"Defense wins championships" may seem like a tired phrase, but it remains true in college football. And on contending teams, a common theme is having an elite defensive line.

Consider this: Since the 2009 season, every national champion except one has ranked in the top 20 nationally of total tackles for loss. The lone outlier is 2012 Alabama, which still finished 29th.

Dominating the trenches is imperative to national success.

Looking ahead to the 2018 campaign, Clemson boasts the undisputed No. 1 unit. We'll highlight the Tigers, along with nine more defensive lines expected to be among the country's best.

While the order has a subjective element because all players—whether stars or depth pieces—develop at varying rates, considerations included 2017 performance and returning production.

All stats from 2017 season unless otherwise noted.

10. Northern Illinois Huskies

Key players: Sutton Smith (29.5 TFL, 14 sacks), Josh Corcoran (8.5 TFL), Ben LeRoy (7.5 TFL), Weston Kramer (19 tackles, 2.5 TFL)

The star: An out-of-nowhere nightmare, Smith secured second-team AP All-America honors with his sensational year. Smith, who arrived at Northern Illinois as a running back, collected eight hurries and three forced fumbles along with 29.5 tackles for loss and 14 sacks. He also returned two fumbles for touchdowns.

What to know: Three starters return from the 2017 roster in Smith (DE), Corcoran (DE) and LeRoy (DT). Rising sophomores Kramer and Jack Heflin will compete for the vacant job at defensive tackle, while Drequan Brown and Matt Lorbeck should be top reserves at end.

9. Michigan State Spartans

Key players: Kenny Willekes (73 tackles, 14.5 TFL), Raequan Williams (31 tackles, 6 TFL), Mike Panasiuk (25 tackles), Jacub Panasiuk (15 tackles), Naquan Jones (13 tackles)

The star: After managing a single pass breakup as a freshman, Willekes exploded for 73 tackles last year. He notched 14.5 stops for loss with seven sacks, adding eight hurries and a forced fumble. The former walk-on earned third-team All-Big Ten recognition.

What to know: The only starter MSU must replace is Demetrius Cooper, the defensive end opposite Willekes. Williams and Mike Panasiuk were full-time starters at tackle in 2017. Jacub Panasiuk (DE) and Jones (DT) are experienced reserves, but the Spartans will be looking for Dillon Alexander and Justice Alexander to provide usable depth.

8. Virginia Tech Hokies

Key players: Ricky Walker (12.5 TFL, 4.5 sacks), Trevon Hill (46 tackles, 9.5 TFL), Houshun Gaines (24 tackles, 7 TFL), Vinny Mihota (24 tackles, 3.5 TFL), Jarrod Hewitt (13 tackles)

The star: Although Hill looks the part of an edge-rushing force, Walker is the unit's anchor at defensive tackle. Two seasons ago, he collected 28 tackles with 6.5 stops behind the line of scrimmage. Walker raised those numbers to 41 and 12.5 in 2017. He also returned one fumble for a touchdown.

What to know: The defensive line will be tasked with buoying a unit that's reloading at linebacker and in the secondary. Mihota will shift from end to tackle, opening a space for Gaines to start with Hill on the ends. Depth is uncertain, but Hewitt and Belmar are a decent base for the reserve unit.

7. Wyoming Cowboys

Key players: Carl Granderson (16 TFL, 8.5 sacks), Youhanna Ghaifan (15.5 TFL, 7 sacks), Kevin Prosser (35 tackles, 5 TFL), Garrett Crall (33 tackles, 5.5 TFL), Sidney Malauulu (22 tackles)

The star: Ghaifan has a legitimate claim to this spot, but Granderson gets the nod for his playmaking. Beyond his 16 takedowns for loss and 8.5 sacks, the rising senior defensive end grabbed two interceptions and returned a fumble for a touchdown in 2017.

What to know: Granderson (DE) and Ghaifan (DT) will lead a seasoned, stacked unit. Prosser, Crall and Josiah Hall complete an impressive rotation at D-end, and three-year contributor Malauulu is pegged as the nose tackle for 2018. Javaree Jackson, Conner Cain and Ravontae Holt should all earn time at interior spots.

6. Michigan Wolverines

Key players: Rashan Gary (66 tackles, 12 TFL), Chase Winovich (79 tackles, 18.5 TFL), Aubrey Solomon (18 tackles)

The star: Winovich deserves more acclaim, but Gary is the man on the Michigan front. The ultimate prize of the 2016 recruiting class, he's backed up that billing in two seasons with the Wolverines. Gary amassed 66 tackles, 12 stops for loss and six sacks during his first year as a starter last season.

What to know: Behind the trio of Gary, Winovich and Solomon, Michigan has a rich supply of talent―but little experience. Michael Dwumfour, the anticipated starter next to Solomon in the middle, had only four tackles last year. Still, there's plenty of promise with him, Kwity Paye, Donovan Jeter and Carlo Kemp. Senior reserves Bryan Mone and Lawrence Marshall will also factor into the rotation.

5. Mississippi State Bulldogs

Key players: Jeffery Simmons (60 tackles, 12 TFL), Montez Sweat (15.5 TFL, 10.5 sacks), Gerri Green (11 TFL, 5 sacks), Cory Thomas (25 tackles in 2016), Fletcher Adams (26 tackles) Braxton Hoyett (21 tackles), Marquiss Spencer (4.5 TFL), Kobe Jones (4.5 TFL)

The stars: Should we even pick between the first-team All-SEC linemen? Nah. Simmons (DE) and Sweat (EDGE) both earned that accolade in 2017, combining for 108 tackles, 27.5 stops for loss and 15.5 sacks. Simmons and Sweat are potential first-round NFL draft picks in 2019.

What to know: Mississippi State is changing from a 3-4 to a 4-2-5, so Green will move from outside linebacker and join Sweat at defensive end. Thomas―who missed seven games because of a foot injury last season―and Hoyett will compete to start alongside Simmons. Adams, Jones, Spencer, Chauncey Rivers and Tre Brown will all contribute in reserve roles.

4. Alabama Crimson Tide

Key players: Raekwon Davis (69 tackles, 8.5 sacks), Isaiah Buggs (51 tackles, 4 TFL), Quinnen Williams (20 tackles, 6.5 TFL), LaBryan Ray (2.5 TFL)

The star: Listed at 6'7" and 306 pounds, Davis is both an imposing presence and a nightmare to block. The defensive end posted eight-plus tackles in four games last season, ending his sophomore year with 69 total stops. He gathered 10 tackles for loss, 8.5 sacks and one interception.

What to know: Alabama's 3-4 defense showcases edge-rushers, so expect Anfernee Jennings, Christian Miller and Terrell Lewis to record the glamorous stats. That shouldn't mitigate the impact of Davis (DE), Williams (nose guard) and Buggs (DE) up front. Ray (DE), Stephon Wynn (DE) and Phidarian Mathis (DT) are the top backups, though Christian Barmore and Tevita Musika could join the rotation.

3. Auburn Tigers

Key players: Derrick Brown (56 tackles, 9 TFL), Marlon Davidson (43 tackles, 6.5 TFL), Dontavius Russell (46 tackles, 6.5 TFL), Andrew Williams (38 tackles), Nick Coe (29 tackles, 4.5 TFL), T.D. Moultry (15 tackles)

The star: A 5-star recruit in the 2016 class, Brown put together a breakout campaign as a sophomore. He accumulated 56 stops with nine tackles behind the line of scrimmage, including 3.5 sacks. Though his NFL future is strictly as a defensive tackle, Brown occasionally shifts to end for Auburn.

What to know: The unit's starters are Davidson, Brown and Russell, likely along with Moultry at the "Buck" spot. Coe―who can play end or defensive tackle―Williams (DT) and Big Kat Bryant (Buck) will be the main reserves. Tyrone Truesdell should also contribute behind Russell at nose tackle.

2. Ohio State Buckeyes

Key players: Nick Bosa (16 TFL, 8.5 sacks), Dre'Mont Jones (20 tackles, 5 TFL), Chase Young (19 tackles, 6 sacks), Robert Landers (10 tackles, 5 TFL), Jonathon Cooper (15 tackles), Jashon Cornell (14 tackles)

The star: Arguably the top player in college football, Bosa returns following a 2017 season in which he earned second-team AP All-America honors. The 6'4", 263-pound defensive end registered 34 total takedowns with 16 tackles for loss, 8.5 sacks and nine hurries as a sophomore. His impact stretches well beyond the simple numbers, as he often attracts two or three blockers.

What to know: Young excelled in limited action last season and will start opposite Bosa. Jones is a proven force at defensive tackle, and Landers should join the starting unit. Cooper and Cornell will be the top D-end reserves, while tackles Haskell Garrett and Antwuan Jackson are the front-runners to assist the rotation.

1. Clemson Tigers

Key players: Clelin Ferrell (18 TFL, 9.5 sacks), Christian Wilkins (60 tackles, 8.5 TFL), Dexter Lawrence (34 tackles), Austin Bryant (15.5 TFL, 8.5 sacks), Albert Huggins (22 tackles, 5 TFL)

The star: Despite the fact that the defensive line flaunts a quartet of potential first-round NFL draft picks, Ferrell stands slightly above the rest. The menacing edge-rusher has collected 110 tackles, 30.5 takedowns for loss and 15.5 sacks in two seasons as a starter. Ferrell has chipped in 16 hurries and two forced fumbles in that span.

What to know: Ferrell, Wilkins (DT), Lawrence (DT) and Bryant (DE) will reprise their starting roles. Huggins will play, and both Richard Yeargin and Nyles Pinckney should be regular factors. Beyond that, Clemson has an intriguing question: Will prized 2018 recruits K.J. Henry or Xavier Thomas overtake Justin Foster and Chris Register to carve out playing time? It's a good problem to have.

All recruiting information via 247Sports. Stats from NCAA.com, cfbstats.com or B/R research. Quotes obtained firsthand unless otherwise noted. Follow Bleacher Report CFB Writer David Kenyon on Twitter @Kenyon19_BR.