Darrel Williams is to Derrius Guice as Derrius Guice was to Leonard Fournette.

That’s the algebraic breakdown of the LSU running back position for the past few years.

Fournette was the lead actor from 2014-16 with Guice serving as understudy for the past two seasons. Guice was being groomed to succeed Fournette, who left for the NFL after his junior season last year, and was thrust into the lead role for most of last season while Fournette was injured.

Williams, who was a bit player for each of Fournette’s three seasons, has become Guice’s understudy and he has emerged this season — not to the degree that Guice did last season, but significantly nonetheless.

Just as Fournette was slowed by injury last season, so too has Guice this season.

Fournette injured an ankle in preseason camp and never fully recovered. He played in just seven games, finishing with 843 yards and eight touchdown after having 1,034 yards and 10 touchdowns as a freshman and 1,953 yards and 22 touchdowns as a sophomore.

Guice took full advantage of his opportunity by leading the SEC with 1,387 yards and scoring 15 touchdowns while establishing himself as a likely high first-round choice if he skips his senior season to enter the NFL in 2018.

An early-season leg injury limited Guice to eight carries against Syracuse on Sept. 24, kept him out of the game against Troy a week later and limited his effectiveness for much of the season.

Guice has clearly gotten healthier in recent weeks and broke out against Ole Miss on Oct. 21, rushing for 276 yards and a touchdown. He almost certainly would have broken his LSU single-game record of 285 yards, set against Texas A&M last season, if coach Ed Orgeron hadn’t given most of the fourth-quarter work to Williams. Guice, who had 252 yards against Arkansas last season, became the first SEC back to have three 250-yard rushing games in his career.

The added opportunities enabled Williams to make some history of his own, becoming the first back in LSU history to have 100 rushing yards and 100 receiving yards in the same game.

Now with three games left in the season, Guice is at or near 100 percent as Williams has established himself as an important part of the offense. Williams is averaging a career-best 5.2 yards per carry and is 47 yards shy of doubling his previous best season yardage total.

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“Darrel is one of our most valuable players,” Orgeron said. “Darrel is an all-around back, first-, second-, and third-down back. He’s very good at protection. He’s probably one of our better backs in pass protection.

“Humble, mature, leadership, hard worker. You ask him to lose weight, he loses weight. He doesn’t say a word. He’s one of our best special teams players. He’s there early to work, smiles every day, hardly ever hurt. I’ve hardly ever heard him complain. He’s the ultimate Tiger.”

Offensive coordinator Matt Canada threw in a new wrinkle against Alabama with a direct snap to Williams that yielded a 54-run. That set up Williams’ 2-yard touchdown as he finished with a team-high 83 yards and Guice had 71 yards.

Canada likes throwing the ball to his running backs and Williams is the No. 2 receiver on the team with 18 catches for 241 yards, including the four catches for 105 yards against Ole Miss.

Guice has been used much less in the passing game, but he did have a season-high five catches for 29 yards against Alabama.

As for rushing, Guice (782 yards and six touchdowns with three games remaining) is still the No. 1 option and in good shape to have a 1,000-yard season while Williams (559 yards and six touchdowns) remains a strong option 1A.