The Trojans' stumble on the Palouse put a serious dent in the Pac-12's CFP prospects.
Slipping nine spots to No. 14 in the AP poll, the Trojans must repair a national image that was already tarnished by a string of uneven performances.
No. 11 Washington State and No. 20 Utah, meanwhile, still have the have the feel of fringe contenders in need of a big move.
Which leaves Washington to carry the mantle.
The Huskies, who barely slipped into the playoffs last season, remain undefeated but have left themselves no room for error when it comes to persuading the CFP selection committee to overlook a nonconference schedule padded with Rutgers, Montana and Fresno State.
They get two ranked opponents — Utah and Washington State — at the end of the regular season, but Petersen wasn't looking past next week's matchup against California.
"I think you just take it play by play," he said.
It might not matter who grabs the third and fourth spots in the playoffs.
Right now, the title race looks like a two-horse affair.
With all due respect to the likes of Oklahoma, Penn State and Georgia, it seems that Alabama and Clemson have separated themselves from the pack and, though the Crimson Tide has held on to the No. 1 spot from the start, the race is tightening.
Second-ranked Clemson has emerged spotless from the toughest part of its schedule, defeating three Top 15 opponents before Oct. 1.
The Tigers get a break next week with Wake Forest, followed by Syracuse and a bye before facing Georgia Tech at home.
"I don't see any weaknesses right now," Virginia Tech coach Justin Fuente said after his team lost to the Tigers on Saturday night.
Clemson coach Dabo Swinney is doing his best to dampen the hype: "Five games don't make a season unless they cancel October and November and give us a bye."
Things aren't going as well for one of the teams expected to challenge Alabama in the Southeastern Conference.
Louisiana State dropped out of the Top 25 after a home loss to Troy on Saturday and now faces a murderous stretch that begins on the road against No. 21 Florida and includes No. 12 Auburn and Alabama over the next month.
In his first full season as head coach, former USC assistant Ed Orgeron is already feeling the heat.
Or maybe it was the silence of a stadium that emptied long before the game against Troy ended.
"We've got to do some soul searching," Orgeron said. "I've got to be a leader. I've got to do my best job ever. Right now."