Stopping run is key for Trojans

Examining the strategies when USC’s defense faces Illinois’ offense:

If there’s one thing that has frustrated USC in recent seasons, it has been defending a mobile quarterback such as Juice Williams, who operates out of a spread offense.

Vince Young was effective in this role when he led Texas to a victory over USC in the Rose Bowl two years ago, and Dennis Dixon burned them in Oregon’s win over USC this season.

In Williams, a 6-foot-2, 223-pound sophomore, the Trojans will face a different challenge. While Young and Dixon used their legs to keep plays alive and were effective passers on the move, Williams’ biggest strength is his ability to carry the ball like a running back.

Just ask Ohio State, which was unable to stop Williams in Illinois’ 28-21 upset victory over the Buckeyes on Nov. 10.

Over the final eight minutes of the game, Williams kept Illinois’ offense on the field with one fourth-down conversion run and two key third-down-and-long quarterback keepers.

Rarely does Williams go down on the first hit. That’s not his style and that could be a problem for USC’s hard-charging defense that loves contact but does not always wrap up ballcarriers.

It was a problem for USC against Young and Dixon, who took advantage of poor tackling by the Trojans. USC has to make sure that does not happen against Williams, who rushed for 774 yards and averaged 5.2 yards a carry this season.

When Williams looks to pass, his main target has been freshman wide receiver Arrelious Benn, who was heavily recruited by the Trojans. At 6-2 and 215 pounds, Benn has the size and speed to keep USC’s secondary busy, but then there’s a drop off.

While Benn led the team with 49 catches during the regular season, he was followed by running back Rashard Mendenhall, who had just 29. Jacob Willis was Illinois’ No. 2 wideout and he had only 18 catches for 256 yards.

So expect USC’s secondary, which has steadily improved this season, to stick to conservative coverages with senior cornerback Terrell Thomas often matched up against Benn.

But passing has not been Illinois’ calling card this season under offensive coordinator Mike Locksley. That responsibility falls on the Illinois ground game, powered by a dominant offensive line.

During the regular season, the Illini -- led by all-Big Ten guard Martin O’Donnell -- did a great job of controlling the scrimmage line and opening holes for Mendenhall, who rushed for 1,526 yards and 16 touchdowns and was named Big Ten offensive player of the year.

That’s how the Illini accounted for a Big Ten-best 266.2 rushing yards per game. Inside-out or outside-in, the Illini love to run and by featuring an assortment of blocking schemes, they can grind down a defense with Mendenhall and Williams.

But that plays into a major strength for USC, which has the best defensive front Illinois has faced. Led by seniors Sedrick Ellis and Lawrence Jackson, the Trojans have the nation’s No. 4-ranked defense against the run.

If Illinois center Ryan McDonald -- a second-team all-Big Ten selection -- struggles to control Ellis, an experienced nose tackle with NFL talent, USC’s defense will definitely have an upper hand.

That’s because the more blockers Illinois has to use on Ellis, the more flexibility the Trojans will have with their linebackers and defensive backs. It will also free up Jackson, who played the best football of his career over the final three games of the regular season.

Summary: Although Williams is known more as a runner than a passer, he can hurt a defense on play-action plays. That’s how Williams completed four touchdown passes against Ohio State and the big reason why USC’s defense can’t just concentrate on stopping the run.

But if the Trojans can force Williams into predictable passing situations, they should have an edge given that Williams has thrown five interceptions in his last five games and has 10 for the season.

lonnie.white@latimes.com