After not being eligible for a bowl game or a conference championship over the past two seasons, USC has risen up enough to become the No. 1 team in the first AP poll of the season.

The rebound isn't complete quite yet - the Trojans now have to win when the lights are on - but for a program that was supposed to be hamstrung for years by NCAA sanctions, this ranking is a validation of the job Lane Kiffin was able to do to keep the program afloat during the down years.

It also shows how important one player can be.

Had quarterback Matt Barkley decided to leave early for the NFL, USC wouldn't be the preseason No. 1 team and might be lucky to be in the top five. But he's back, and so is USC with all the expectations and pressure of being considered the top team in the country once again.

On the flip side, this is the first ranking to come out since LSU lost Heisman finalist Tyrann Mathieu, who was booted off the team for alleged substance use. The Tigers are No. 1 in the preseason Coaches' Poll - which actually matters more in terms of the BCS rankings - but fell to third behind USC and Alabama in the AP.

It doesn't really make a difference for LSU -- if it gets through the season clean, with a win over Alabama, it's going to play in the BCS Championship Game and it's going to finish the year as the No. 1 team in AP by going 14-0.

For the Trojans, who were ranked third in the preseason Coaches' Poll, the top spot in the AP rankings will be justification and validation for down the road. If there's another scenario like last season, with Alabama losing to LSU in a regular-season squeaker, then the Coaches and Harris polls won't have any problem making sure USC is in the top two. Everyone would want to see an undefeated AP No. 1 team play the LSU-Alabama winner for the national title.