Complicating matters, the Trojans' defense suffered a couple of key injuries in the Arkansas game. Starting cornerback Terrell Thomas is likely out for the season with a knee injury, severely testing USC's depth at what was already its thinnest position (fifth-year senior John Walker, primarily a special teams player, will start in his place). Meanwhile, the Trojans' most experienced linebacker, senior Dallas Sartz, and his top backup, freshman Brian Cushing, are sidelined for at least the Oregon game with shoulder injuries. Third-year sophomore Thomas Williams will get the starting nod at strongside linebacker.

For all the attention afforded Leinart, Bush & Co., the Trojans' dominant defense was just as integral to their past two national title teams. The 2003 and '04 squads both ranked No. 1 in the country in rushing defense and in the top 20 in scoring defense while producing a staggering 105 sacks. With this year's offense performing at an NFL-caliber level, the Trojans can afford a little slippage on defense, but they also can't assume the offense will score 50 every time it steps on the field. Nearly every national champion encounters at least one game in which it has to pull out a victory in the fourth quarter. For USC, it could come as soon as this weekend against Oregon (not likely) or next weekend against Arizona State (somewhat more likely).

If the Trojans give up 40 points or 500 yards to either the Ducks or Sun Devils -- or, of course, if they lose one of those games -- their aura of invincibility will take a hit. Suddenly the field will seem wide open. On the other hand, if USC beats those teams by the same healthy margin that it amassed against Hawaii and Arkansas, well, feel free to let the "best ever" debate begin.

Scoping out the country

• Last weekend saw an unusually high number of major injuries to high-profile players. In addition to USC's defensive losses, cross-town rival UCLA lost top receiver Junior Taylor for the season with a knee injury, a major blow for a team whose passing offense is really clicking. Florida lost its No. 2 receiver, Andre Caldwell (broken leg), for the season, and its top pass-rusher, Ray McDonald (partially torn ACL), for four-to-six weeks. Boston College QB Quinton Porter (sprained ankle) is doubtful for Saturday's game against Clemson.

• Paging Lance Leggett. For two years, we've been hearing that the 6-foot-3 sophomore is going to be the next great Miami receiver (his bio on the school's official Web site claims he "reminds observers of Randy Moss.") He averaged 20.5 yards on 17 catches as a freshman, but in two games this year he's caught one pass -- for minus-8 yards. Admittedly, the 'Canes first two opponents, Florida State and Clemson, presented some pretty stiff pass defenses (Miami concentrated almost entirely on running the ball in the second half and overtime last week). If he can't do it against Colorado's secondary on Saturday, he could have problems.

• In what has become the recurring theme of LSU's season, weather could play a significant role in Saturday night's showdown with Tennessee. While Baton Rouge is not currently in the projected path of Hurricane Rita, it's close enough that the area is expected to be doused with thunderstorms throughout the weekend, causing possibly muddy conditions at Tiger Stadium, which could be a severe disadvantage for LSU. One of  LSU's greatest assets is its considerable speed on the outside, such as receiver Skyler Green. A game played primarily in the trenches would seem to favor the Vols.

• Here's a matchup you don't see often: On Saturday, the nation's top-ranked rushing offense (Minnesota, 335 yards per game) faces the No. 1 rushing defense (Purdue, 18.0 yards per game). Admittedly, both sides' numbers are inflated due to the less-than-stellar competition they've faced, but they're not entirely deceiving, either. With Laurence Maroney and a veteran offensive line, the Gophers are a dominant running team, and with 11 returning starters, the Boilers were expected to field one of the nation's top defenses. Something's got to give in this one.

• Ohio State's offense isn't inspiring confidence in Columbus following another shaky outing against San Diego State. I know Jim Tressel likes to play things close to the sweater-vest, but there's no excuse why a unit with that many weapons (Troy Smith, Ted Ginn Jr., Santonio Holmes) shouldn't score at will on inferior opponents. It does appear Tressel has at least committed to Smith as his trigger-man (he kept him in until the fourth quarter, and Smith ran for a team-high 87 yards on 14 carries), but it will be interesting to see how he performs against an awfully tough Iowa defense.

• Border rivals New Mexico and UTEP have played each other 72 times, but Saturday night's game at the Sun Bowl will mark the first time since 1957 both teams have entered their matchup undefeated. The Lobos, which have finally developed a decent passing game to complement standout RB DonTrell Moore, earned a measure of respect when they beat Missouri two weeks ago. It's hard to gauge Mike Price's Miners, though, because despite the presence of star QB Jordan Palmer and RB Tyler Ebell, UTEP needed double overtime to survive Houston last weekend.

Some quick predictions

After debuting at a respectable 6-3 in the new "stick to the scores" format, I think it's here to stay...

• LSU 27, Tennessee 20
• USC 41, Oregon 24
• Virginia Tech 21, Georgia Tech 13
• Ohio State 23, Iowa 17
• Michigan 28, Wisconsin 24
• Miami 31, Colorado 14
• Purdue 24, Minnesota 21
• Clemson 20, Boston College 14
• Northwestern 27, Penn State 24

Stewart Mandel covers college sports for SI.com.