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"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.