Losses by LSU and Ohio State likely close door

Saturday came and went without a single upset in the upper half of the BCS standings.

Only three top-15 teams lost, and all of them fell to a higher-ranked opponent.

Although that might sound like an uneventful weekend, there were actually a few significant developments in college football's title chase.

The two teams that played in last year's BCS National Championship Game -- LSU and Ohio State -- were both handed their second losses of the season. And even though a second loss didn't eliminate LSU a year ago, the Tigers and Buckeyes now find themselves needing an improbable amount of help just to stay alive in their conference races. For either to be mentioned as a national contender again in 2008 might require a minor miracle.

USC's situation isn't nearly so desperate, but the Trojans also had a bad weekend from a BCS perspective, despite an important road win over Arizona.

Penn State's victory at Ohio State significantly increased the chances that there will be at least one undefeated team from a major conference -- a team USC won't be able to pass in the standings. The Nittany Lions have only three games remaining and will be a strong favorite in all of them (at Iowa and home versus Indiana and Michigan State). If PSU can run the table, that essentially removes one of the two spots in the BCS Championship Game from USC's reach.

If Alabama or a Big 12 team (Texas or Texas Tech) also goes undefeated, that's obviously the worst-case scenario for the Trojans. But even a one-loss champion from the SEC or Big 12 could be a difficult hurdle for USC because of the perceived strength of those conferences relative to the Pac-10.

One hope for the Trojans is that twice-beaten Missouri will win the Big 12 North and then knock off whichever highly ranked team emerges from the South in the conference title game.

After Saturday's games, hope for such a scenario to also play out in the SEC is fading.

Alabama's win combined with LSU's loss means the Tide could now lose in Baton Rouge and still reach the SEC championship game with an 11-1 record, provided they win home games against Mississippi State and Auburn. Meanwhile, Saturday's SEC East showdown between Florida and Georgia will produce a winner that is also just a few weeks away from entering the SEC title game with a single loss.

While it's certainly not automatic that USC would finish behind a once-beaten SEC champion in the polls, it is highly probable that the Trojans would be ranked lower in the computers. That means USC would need to get a significant edge over the SEC team from the human voters, which might not be so easy, given that some of them might still give consideration to the SEC having produced the last two BCS champions.

Like USC, Oklahoma (7-1) is also negatively impacted by Penn State's much-improved chance to finish unbeaten, and the Sooners' window of opportunity to pass Texas is also closing. Although OU wouldn't be mathematically eliminated by a Texas win over Texas Tech on Saturday, any realistic scenario for Oklahoma to win the Big 12 South requires the Red Raiders to pull off the upset.

If Texas Tech can win that game, there would be a chance for Oklahoma to force a three-way tie atop the South by beating Tech later in the month. Even then, there would be no guarantees for the Sooners, but it's probably the best opportunity they have left.

Any questions about whether Penn State has a chance to jump over Alabama should be answered by this week's BCS standings. Even after the impressive road win over Ohio State, PSU is still trailing the Tide in both polls and five of the six computers. And Alabama has a couple of highly ranked opponents left on its schedule (assuming an SEC championship game), while Penn State has none.

Nittany Lions fans are understandably disturbed by this, having seen their team go undefeated five times under Joe Paterno and win a national title in only one of those seasons. But the message seems clear: Unless Alabama loses or the Texas-Texas Tech winner takes a loss later in the season, Penn State will be bound for the Rose Bowl instead of the BCS National Championship Game.

Brad Edwards is a college football researcher at ESPN. His Road to the BCS appears weekly during the season.