Two down, four to go.

Stanford and USC have secured victories in rivalry games this season, but there are four left in the Pac-12 with both berths in the league championship game still on the line.

Colorado controls its own destiny when it hosts Utah on Saturday. With a win, the Buffaloes claim the Pac-12 South Division outright. If Colorado loses, it drops into a tie in the standings with USC, and the Trojans, who have finished conference play, will win the South because they beat the Buffaloes 21-17 back on Oct. 8.

The showdown between Washington and Washington State in the Apple Cup on Friday night will decide the Pac-12 North. Both teams are 7-1 in conference play.

The league title game is set for Friday, Dec. 2, at Levi's Stadium in Santa Clara, California.

Stanford won the Big Game against rival Cal 45-31 last weekend and now finishes the regular season at home against Rice, while the Golden Bears host UCLA. The Trojans, who beat the rival Bruins 36-14 at the Rose Bowl, host longtime non-conference rival Notre Dame on Saturday.

A look at the conference rivalry games this weekend in the Pac-12:

WASHINGTON-WASHINGTON STATE

Series began: 1900.

Series record: Washington leads 70-32-6.

Trophy: Apple Cup.

Why it's a big deal: The game is for the Pac-12 North title, which has been claimed by either Sanford or Oregon since the league expanded and a conference championship game was created in 2011.

Best game: The most memorable game in recent years came in 2012. Washington State trailed 28-10 in the fourth quarter but Cougars quarterback Jeff Tuel led his team to a pair of touchdown drives. After Andrew Furney's field goal tied it, Washington's Travis Coons missed a 35-yard FG attempt and sent the game to overtime. Furney's field goal gave Washington State a 31-28 victory in the biggest comeback in Apple Cup history.

This year: The game is crucial to the Huskies (10-1 overall) to preserve a shot at the College Football Playoff. Washington is No. 6 in both the CFP rankings and the Top 25.

OREGON-OREGON STATE

Series began: 1894.

Series record: Oregon leads 63-46-10.

Trophy: Called the Civil War, the game's unofficial prize is the Platypus Trophy, awarded each year to the alumni association of the winning team. Lore has it that the platypus was chosen because it has a duck bill and a beaver tail, so it represents the mascots of both schools.

Why it's a big deal: The winner will avoid finishing in the Pac-12 North basement. Three teams — Oregon, Oregon State and Cal — are 2-6 in league play with one game to go.

Best game: The Ducks entered the 1994 Civil War tied with USC for the Pac-10 championship and needed a win to clinch their first Rose Bowl berth since 1957. Trailing 13-10, Danny O'Neil drove the team 70 yards, hitting Dino Philyaw for a 19-yard touchdown with 3:47 to play, giving Oregon a 17-13 victory.

This year: The Ducks have just four wins, but they're coming off a 30-28 upset of No. 11 Utah. The chances are slim, but with a fifth victory Oregon could be considered for a bowl bid if there are not enough six-win teams to fill all the games.

ARIZONA STATE-ARIZONA

Series began: 1899.

Series record: Arizona leads 48-40-1.

Trophy: Territorial Cup, which is recognized by the NCAA as the oldest rivalry trophy.

Why it's a big deal: It's at Arizona Stadium, which is key because the home team has won in each of the past three seasons and the Wildcats are still looking for their first conference win. Arizona and Rutgers are the only two teams in the Power Five conference that are winless in their leagues.

Best Game: Arizona was ranked No. 12 and Arizona State was No. 8 in 1975 when the two teams met with the Fiesta Bowl in reach. Arizona State receiver John Jefferson made an amazing catch to narrow Arizona's lead to 14-10. While the lead changed hands in the second half, Sun Devils quarterback Dennis Sproul's 1-yard keeper was the go-ahead touchdown that sent undefeated ASU on to a victory over Nebraska in the Fiesta Bowl.

This year: At 5-6 overall, Arizona State needs one more win to become bowl eligible. The Sun Devils have made the postseason for the last five straight years. Arizona hasn't gone winless in conference play since 1957.

UTAH-COLORADO

Series began: 1903.

Series record: Colorado leads 31-28-3.

Trophy: It's been called the Rumble in the Rockies, but there's no official trophy. The rivalry was dormant for several decades before it was revived when both teams joined the Pac-12 in 2011.

Why it's a big deal: Utah's true rivalry game is the Holy War against BYU. Colorado has the Rocky Mountain Showdown against Colorado State. But a win against a Pac-12 recruiting foe never hurts.

Best game: In 1961, the Utes were just 5-3 heading into the game against No. 8 Colorado in Boulder. The undefeated Buffaloes jumped out to a 6-0 lead but Utah scored three unanswered touchdowns and held off the Orange Bowl-bound Buffaloes 21-12.

This year: The No. 21 Utes fell out of the running for the Pac-12 South title with a loss to Oregon last weekend. The No. 9 Buffaloes, who haven't been ranked this high since 2002, must win outright to claim the Pac-12 South.