On paper, it appears to be a huge mismatch. One of those David vs. Goliath scenarios.

But it's probably not the mismatch one would think about when a team like Navy takes on a top 10 Southeastern Conference team like South Carolina.

Most would quickly conclude that it's the Gamecocks -- the defending SEC East champs -- who would have the clear advantage in nearly every facet going into Saturday night's game at Williams-Brice Stadium.

Not so fast.

Five times in the last eight seasons, the Midshipmen have led the nation in rushing. The Midshipmen's option-style attack led the nation in rushing for four straight seasons from 2005-08, while averaging more than 321 yards per game on the ground.

This season is no exception. Navy is averaging an eye-popping 400.5 yards per game. A year ago, Navy had nearly 600 yards of total offense, including 521 rushing yards, as it crushed East Carolina, 76-35, on the road.

The Gamecocks, meanwhile, have struggled defensively in their first two games against East Carolina and Georgia, giving up an average of 39.5 points and 390.5 yards a game. After two weeks, USC is ranked 110th nationally in scoring defense and 76th in total defense. That's a far cry from a year ago, when the Gamecocks had the nation's 12th-ranked rushing defense.

"We're just not tackling very well right now," said South Carolina defensive coordinator Ellis Johnson.

"We've got kids out there who just can't seem to function right now."

Too many missed tackles, too many mental mistakes and too many blown assignments have the Gamecocks shuffling some of their personnel, especially in the secondary.

DeVonte Holloman, a spur, was moved to strong safety during Monday's practice, while D.J. Swearinger was switched from strong safety to free safety. Jimmy Legree, who started at free safety in the first two games, will back up Swearinger.

"Jimmy didn't do a very good job of tackling on Saturday, and he knows it," said USC defensive backs coach Lorenzo Ward.

"In this game, you need physical safeties that can fight through blocks and get to the pitch man."

The play of the secondary and the linebackers will be a key for the Gamecocks.

"The option is really all about perimeter football," said Gamecocks defensive line coach Brad Lawing.

"The option is built to negate a defensive line. They squeeze everything down and they try to get everything outside. A lot of the time with the option you're in one-on-one situations, so you've got to do a good job of tackling in open space," he said.

Stopping the Midshipmen will mean playing smarter, more disciplined defense than the Gamecocks have played up to this point in the season.

"We've got to be fundamentally sound," said USC defensive tackle Travian Robertson. "There is no room for errors against these guys. We've got to play very sound up front and everyone has to play their assignments. You make one mistake up front or on defense, and they'll hit a big play on you."