STANFORD, Calif. — Stanford made one thing clear with its upset victory over Pac-10 leader Oregon: There will be a full-fledged scramble for the conference title over a chaotic final four weeks.

STANFORD, Calif. (AP) — Stanford made one thing clear with its upset victory over Pac-10 leader Oregon: There will be a full-fledged scramble for the conference title over a chaotic final four weeks.

With the Ducks losing their first conference game 51-42 to the Cardinal on Saturday, there are five teams with a legitimate shot to at least share the championship and a seemingly infinite number of permutations for how the race will shake out.

Few thought at the beginning of the season that a scenario with Stanford and Arizona finishing ahead of Southern California and Cal was a possibility. But that's just what the standings show after the first Saturday in November.

"This is best opportunity Stanford football has had in the last 10 years to express who this team is as a football team, and they expressed it," Cardinal coach Jim Harbaugh said.

A one-win team in 2006, Stanford (6-3, 5-2) has moved into the AP poll at No. 25 for the first time in eight years behind the strong running of Toby Gerhart and the poised passing from redshirt freshman Andrew Luck.

Following their most meaningful win in years, the Cardinal are already a Pac-10 contender in Harbaugh's third season. It's surprised even the most ardent Cardinal supporters who rushed the field afterward.

"I was out there and people were saying, 'I can't believe you won,'" said Gerhart, who set a school record with 223 yards rushing. "I was like, 'Have faith.' We were confident. There was definitely no fear going into this game."

The victory also gave a big boost to the conference's other two-loss teams, No. 11 Southern California and Oregon State.

But heading into the stretch run, only No. 14 Oregon (7-2, 5-1) and No. 18 Arizona (6-2, 4-1) can win the title without any help. The biggest game left will come when the Ducks visit the Wildcats on Nov. 21.

"We're still at the top of the Pac-10 right now," Oregon linebacker Spencer Paysinger said. "The cushion is not as big, that's all. So we have to keep working. You'll see a different team against Arizona State. We still have this thing in our grasp."

Oregon can make it to the Rose Bowl with home wins against Arizona State and Oregon State, and the win against Arizona.

The Ducks have already shown the ability to bounce back this season, winning seven straight games after losing the opener to No. 6 Boise State.

"We've been in this spot before. We have to go back and battle," tight end Ed Dickson said. "The only thing we can control is how we play and that starts again on Monday."

The Wildcats can clinch their long-awaited first Rose Bowl berth by beating the Ducks, winning at USC on Dec. 5, and splitting road games against California and Arizona State.

Any other slipups could open the door for one of those three two-loss teams to win at least a share of the title and possibly a Rose Bowl berth, depending on how the tiebreaker plays out.

"Our goal is to win the Pac-10 championship," Harbaugh said. "We're still alive for that. We'll go next week down to USC and play a great football team down there and try to keep those hopes alive."

With the win over Oregon, the Cardinal became bowl eligible for the first time in eight years. That sets up a big showdown on Saturday against the Trojans, who were being counted out of the conference race just a week ago following a 47-20 loss at Oregon.

"For whatever reason, you guys have amnesia," USC coach Pete Carroll said. "You forget that every year, it ain't over 'til it's over, and the season keeps rolling and games happen and the matchups occur. Everybody wants to call it. What's the point? Just play the darn season. It's a hard conference."

USC has been counted out of the Pac-10 race during a run of seven straight titles, only to capitalize on late-season losses by the competition.

The Trojans earned a share of the title in the first year of the run only because Washington State lost the Apple Cup to Washington. The Cougars got the Rose Bowl berth, the last Pac-10 team other than USC to do so.

The Trojans won the title easily the following three seasons, but things have been more complicated since then. USC lost its finale to UCLA in 2006, costing the Trojans a possible berth in the BCS title game and allowing California to win a share of the conference title.

USC looked out of the race after losing at Oregon in 2007 for its second conference loss. The Trojans ended up sharing the title with Arizona State when Ducks quarterback Dennis Dixon went down with a knee injury and Oregon lost its final three regular season games.

Oregon State was poised to end USC's Rose Bowl run last year before losing its season finale to Oregon, giving the Trojans an outright title.

This time, the Trojans know their chances depend on winning out.

"We've got to take care of business next week," Carroll said. "We've got to get those guys. That's a huge, huge opportunity for us. They're playing lights-out. I don't know how we're going to slow them down. I don't know, but we'll figure that out."

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AP College Football Writer Andrew Bagnato in Tempe, Ariz., contributed to this report.