It took a while — seven weeks to be exact — but three teams have finally distinguished themselves as the cream of the crop in the Pac-12.

Two of them are the usual suspects: No. 2 Oregon is on the path to play in the National Championship game and No. 11 USC, while underwhelming at times, has shown it has elite ability.

No. 8 Oregon State is a completely different story.

The Beavers were awful last year, finishing just 3-9 and losing their home opener to FCS Sacramento State. Sure, they had some potential entering this season — quarterback Sean Mannion returned for a sophomore season and cornerback Jordan Poyer was second-team All-conference in 2011. But even with that, no one had any expectations for the Oregon State squad.

Now, the Beavers are 5-0 with wins over then-ranked Wisconsin and UCLA, but their victory at BYU this week was their most impressive win to date.

Mannion was held out of the game in Provo, Utah, thrusting junior Cody Vaz into a game against the nation’s top rated run defense.

Entering the game, Vaz was 6-for-17 in his college career and hadn’t started a game since high school, but the junior took the reins and led Oregon State to its fifth straight victory. To make the win even more impressive, starting running back Storm Woods left the game late and the Beavers didn’t even blink.

No. 11 USC is another member of the upper tier, but almost by default. The Trojans are as talented as any team in the country, but for some reason they have yet to put together a complete game, at least since their week one 49-10 victory against Hawaii.

USC’s four victories since have been by just about 13 points a game against a fairly weak crop of teams with a 10-15 combined record.

It’s still too early to completely crown the big three though, as Arizona State and Stanford linger behind as fringe contenders.

The Cardinal claim has some legitimacy — it beat the Trojans at home and lost on an extremely questionable call at No. 7 Notre Dame. Still, that loss was its most impressive performance since the USC win.

And then there is the enigma known as Arizona State. The Sun Devils have just one loss, on the road against Missouri, but their schedule has been paper thin.

With that said, Arizona State sports the eighth best overall defense in terms of yardage and is second in sacks with 26.0. In a way, the Sun Devils are the polar opposite of their in-state rival Wildcats.

The battle between Arizona and Oregon was answered resoundingly in late September. This week Arizona State will get a chance to try its own style against the conference-leading Ducks.

The lower tier of UCLA, Arizona and Washington has shown potential this season, as all three have been ranked at one point or another. But both the Wildcats and Huskies are riding multiple-game losing streaks, albeit against ranked teams, and the Bruins didn’t look great at home against Utah, even if they did manage to take the win.

This week Arizona and Washington will get the chance to prove who is the better team while UCLA rests up for its matchup in Tempe in two weeks. Still, none of these teams have shown the consistency or ability to really contend for the Pac-12 title.

1. No. 2 Oregon
(6-0, 3-0 Pac-12) Last week: 1
Week seven: Bye
This Week: at Arizona State

2. No. 8 Oregon State (5-0, 3-0) LW: 2
Week seven: (W 42-24 at BYU)
This Week: against Utah

3. No. 11 USC
(5-1, 3-1) LW: 4
Week seven: (W 24-14 at Washington)
This Week: against Colorado

4. No. 22 Stanford
(4-2, 2-1) LW: 3
Week seven: (L 20-13 OT at No. 7 Notre Dame)
This Week: at Cal

5. Arizona State
(5-1, 3-0) LW: 6
Week seven: (W 51-17 at Colorado)
This Week: at No. 2 Oregon

6. UCLA
(5-2, 2-2) LW: 7
Week seven: (W 21-14 against Utah)
This Week: Bye

7. Arizona
(3-3, 0-3) LW: 8
Week seven: Bye
This week: against Washington

8. Washington
(3-3, 1-2) LW: 5
Week seven: (L 24-14 at No. 11 USC)
This Week: at Arizona

9. California
(3-4, 2-2) LW: 9
Week seven: (W 31-17 at Washington State)
This Week: against No. 22 Stanford

10. Utah
(2-4, 0-3) LW: 10
Week seven: (L 21-14 at UCLA)
This Week: at No. 8 Oregon State

11. Washington State
(2-5, 0-4) LW: 11
Week seven: (L 31-17 against Cal)
This Week: at No. 14 Oregon State

12. Colorado
(1-5, 1-2) LW: 12
Week seven: (L 51-17 against ASU)
This Week: at No. 11 USC