TUCSON, Ariz. — At last, the Pac-10 is down to two.

When No. 10 Oregon and No. 16 Oregon State meet in the Civil War on Dec. 3, a Rose Bowl berth will be on the line for both schools — a first in a bitter rivalry that kicked off in 1894.

For one year, at least, it’ll be the War of the Roses.

“This is crazy,” Oregon quarterback Jeremiah Masoli said after running for three TDs and throwing for three more in a 44-41 double-overtime victory over Arizona on Saturday night.

Crazy is also an apt description for the Pac-10 this season. Clarity finally came on Saturday.

USC awoke with a mathematical chance of returning to the Rose Bowl, but the Trojans weren’t even on the field when their record seven-year reign ended. Oregon State eliminated USC with a 42-10 rout of Washington State in Pullman.

California knocked Stanford out a few hours later in a 34-28 Big Game victory at Stanford, a result met with glee in Berkeley.

“It showed tonight that they aren’t ready to play in the Rose Bowl,” Cal quarterback Kevin Riley said. “Everybody was talking about how Stanford was going to win. We just shut up and played.”

Then the spotlight shifted to Tucson for Oregon-Arizona, the latest in a series of riveting games on the West Coast this autumn.

Some Pac-10 coaches have groused about the league’s round-robin format. They’d rather go to eight league games, giving teams a chance to fatten their records with a nonconference opponent.

But if the Pac-10 didn’t have a round-robin, the league would have been poorer for it this season.

What if Oregon had skipped USC? The Ducks established themselves as the team to beat in a 47-20 whipping of the Trojans on Oct. 31.

What if Stanford had a bye against Oregon? The Cardinal asserted their newfound strength in a 51-42 victory over the Ducks on Nov. 14.

And what if Arizona and Oregon had missed each other? With a national TV audience watching, the Wildcats and Ducks produced a 3-hour, 47-minute infomercial for Pac-10 football.

“There’s no rest in this league,” Oregon coach Chip Kelly said on the Arizona Stadium field late Saturday night. “And when you end up getting a chance to call yourself a champion in this league, you’ve actually earned it because you’ve got to play everybody.”

Arizona was the first team to 20 points, 30 points and 40 points and still lost.

It was another heartbreaker for the Wildcats, who lost at Washington when a pass bounced off an Arizona receiver’s foot and the Huskies intercepted and returned it for a touchdown.

The Wildcats remain the only Pac-10 team that hasn’t played in the Rose Bowl — and their drought is 32 years and counting.

“We got so close, but we just have to look at the big picture,” said Arizona coach Mike Stoops, who inherited a 2-10 team after the 2003 season.

The Wildcats nearly kept their Rose Bowl hopes alive with a defense that thwarted Oregon for much of the night.

The Ducks mustered only two touchdowns in their first 10 possessions. But with Masoli at the controls, they exploded for four TDs and a field goal on their final six possessions, including two in overtime.

Masoli tied it with a touchdown pass to Ed Dickson with six seconds left, then won it with a 1-yard run in the second overtime.

“There was nothing that our players did that surprised me,” Kelly said.

Nick Foles threw four TD passes for Arizona (6-4, 4-3), which was eliminated from Rose Bowl contention.

“That was a real tough loss, especially for the kids,” said Arizona coach Mike Stoops, whose team lost for the first time at home. “We did really well tonight with getting Oregon out of their comfort zone. They’ve got a very good quarterback, and that is definitely what makes the difference.”

Facing relentless pressure from the Wildcats, Masoli struggled at times, fumbling twice and throwing an interception that led to Arizona’s first score.

But Masoli was there when the Ducks needed him most. He was unstoppable late in the game, then took over in overtime.

After Masoli hit Jeff Maehl for a 4-yard score on Oregon’s first overtime possession, Foles hit Juron Criner with a 3-yard strike to tie it at 38-38.

In the second OT, Oregon forced Arizona to settle for a 41-yard field goal by Alex Zendejas.

A touchdown would win it for Oregon, and Masoli quickly produced it.

He hit Dickson for 22 yards, and three plays later Masoli bulled over from a yard out.

“I was just resolved,” Masoli said. “I’m just really happy with the result and really proud of our guys. They just played their hearts out the whole time.”

Oregon got plenty of lucky bounces and needed every one.

Two Masoli fumbles bounded away from Arizona defenders, and the Wildcats also dropped an interception.

The Ducks might have guessed it was their night when kicker Morgan Flint’s 43-yard field goal hit the crossbar and bounced through the uprights, tying the game at 24-24 in the fourth quarter.

“How far was it?” Kelly said.

Told it was 43 yards, Kelly smiled and said, “That’s his limit.”

The Ducks and Beavers have taken this season to the limit.

The Ducks opened with a 19-8 loss at No. 14 Boise State — a game that turned tailback LeGarrette Blount into a household name — and then pulled out a two-point victory over mediocre Purdue in Eugene.

“Everybody else counted us out, but we never counted ourselves out,” Oregon cornerback Cliff Harris said.

The same could be said for the Beavers. On their way to a 2-2 start, they had to kick a last-second field goal to beat UNLV and then lost to No. 17 Cincinnati at home.

“Our team rises to the occasion,” Oregon State quarterback Sean Canfield said.

Both teams will catch their breath this week, then start gearing up for the Civil War.

Oregon shipped its gear back to Eugene in a semi-trailer with “Keep on Duckin’” splashed across the side. The slogan has never been truer.

“We’ve taken everybody’s best shot so far,” Kelly said, “And we know we’ve got an unbelievable game coming up on a Thursday night with Oregon State, and they’re a tremendous football program.”