What a difference a week makes in college football. At this time last week, the juggernaut that is Wake Forest led the nation in total defense. One week later, though, the Demon Deacons have tumbled to No. 12 overall.
Teams such as South Carolina, Notre Dame and Texas occupied space in this section a week ago. However, similarly bad weeks, such as allowing 550 rushing yards like Texas did, led to those schools falling out of our defensive power rankings.
Our No. 1 defense last week, Alabama, had the week off. Where will they rank this week? They have a tough test this weekend against Johnny Manziel and Texas A&M in College Station.
Here's a look at the top 10 defenses in all of college football as we near Week 3.
Oklahoma is used to playing solid defense. That reputation took a bit of a hit in 2012, but after two weeks, it appears the Sooners are back.
The Sooners have allowed just seven points in two games thus far. In total defense, they rank No. 20 overall, giving up an average of 276 yards per game.
Oklahoma faces Tulsa this weekend, so expect another outstanding effort by the OU defense. The Golden Hurricane currently rank No. 90 overall in total offense.
Led by a very good defensive line and senior corner Aaron Colvin, the Sooners face their toughest test to date in two weeks when they travel to South Bend to face Notre Dame.
The Oregon Ducks currently rank No. 2 in total offense. They've scored 125 points in two games. How does that relate to their defense?
Considering the pace at which they play and how much they score, it is remarkable the Ducks have only given up 13 points in the first two weeks of the season.
Oregon is giving up 320 yards per game, but much of that is due to the Ducks playing soft coverage late in games when they have an insurmountable lead.
Tennessee comes to Eugene this weekend. The Vols score often, too, so this will be a big test for Nick Aliotti's defense.
It's a bit unusual to see the Tigers this low on the list. That's what happens when you put as many players in the NFL in one season as the Tigers did.
Through two weeks, the Tigers are winning with offense. That has to be encouraging for head coach Les Miles, as the offense has held the team back in recent seasons.
However, it is defense that LSU is known for. Despite returning just four starters, the Tigers are allowing just 277 yards per game.
The Tigers welcome Kent State and Auburn to Death Valley the next two weeks before a big matchup with Georgia on September 28.
The Seminoles were off this past weekend after their Labor Day destruction of Pitt on national television.
They welcome Nevada and Bethune-Cookman to Tallahassee in each of the next two weeks, so expect those defensive numbers to continue to improve.
The Seminoles won't truly be tested until October 19, when they travel to Clemson in what should be one of the best games of the season.
FSU is loaded on the defensive line and has one of the more experienced secondaries in the nation, led by senior Lamarcus Joyner. Look for this group to create several turnovers in the next few weeks.
Led by senior middle linebacker Max Bullough, most believed the Spartans would be strong on defense in 2013. They returned six additional starters, including three members of the secondary.
Two weeks into the season, the Spartans currently rank No. 3 in total defense. They are giving up just 179 yards per game.
While Bullough is an All-American candidate, he isn't the only great player the Spartans have on defense. Junior defensive end Marcus Rush and senior defensive tackle Tyler Hoover are both among the best at their respective positions in the Big Ten.
As a team, Michigan State has eight sacks thus far. This is a swarming defense that looks forward to their trip to South Bend on September 21.
Sure, they haven't been tested yet, but Wisconsin has been exceptional on defense thus far.
Currently the No. 1 total defense in the country, the Badgers are allowing just 162 yards per game. They've pitched two shutouts thus far on the season, which makes them the top scoring defense in the country, too.
Interestingly enough, three teams have yet to allow a point, with the Badgers being the only one to play two games. One of those teams, Arizona State, is Wisconsin's next opponent. Points should be at a premium in this contest.
Led by one of the best front-seven units in the country, the Badgers should be tough to run on all season. This weekend will be a big test, though, as Wisconsin faces one of the best running backs in the country in Marion Grice.
The Gators suffered their first loss of 2013 last weekend at the hands of Miami. Don't blame the defense, though. Florida held the 'Canes to just 212 total yards.
Through two weeks, the Gators are giving up an average of 208 yards per game, good for No. 5 in total defense. Unlike some teams on this list, the Gators have played a quality opponent in both weeks.
Florida is off this week and will host Tennessee next weekend.
James Gayle, Kyshoen Jarrett and Detrick Bonner
After a tough opening week loss to Alabama, the Hokies did what they were supposed to do by blowing out Western Carolina. They were a muffed punt away from a shutout last weekend.
The Hokies had three interceptions last weekend and returned one for a touchdown. They currently rank No. 4 in total defense.
They face an East Carolina team Saturday that throws the ball more than 40 times per game. It will be important for the Hokies' defensive line to get pressure on the Pirates' QB Shane Carden to slow down the Pirates' fast-paced offense.
Stanford cornerback Alex Carter
It was an impressive debut for the Stanford Cardinal last week. They were off Week 1, and the Cardinal defeated San Jose State, led by their outstanding quarterback, David Fales, rather easily.
Stanford held the Spartans to just 35 rushing yards at 1.5 yards per attempt. Overall, they allowed 251 yards.
The Cardinal head to West Point this weekend for a meeting with Army. Expect another big day for Stanford's outstanding defense.
They return home on September 21 for a big matchup with Arizona State.
After a week off, you didn't expect the Tide to lose their spot as the nation's top defense, did you?
Alabama was very impressive in a Week 1 win over Virginia Tech. They gave up just 59 yards through the air. The week off was probably good for the run defense, as Nick Saban was none too happy with giving up 153 yards on the ground. It is important to note that 77 yards came on one play.
Alabama faces the only team that beat them in 2012 this weekend when they travel to College Station to face Texas A&M in a battle of top-10 teams.
Will they remain in this spot next week after facing Johnny Football?