The latest contender: Washington.
The Huskies have another opportunity to unseat both the next two weeks and vault themselves into the national championship picture for the first time in at least a decade. No. 15 Washington (4-0, 1-0) plays at fifth-ranked Stanford (4-0, 2-0) on Saturday night before hosting No. 2 Oregon next week.
The outcomes might not only determine which way Washington's season goes, they also could decide whether there will be any shuffling in the Pac-12's North Division or just a continuation of the two-team dominance before the Cardinal and Ducks meet at Stanford Stadium on Nov. 7.
"This team's really cool," Washington coach Steve Sarkisian said. "It's not about what might occur down the road, the what-ifs. It's about what is occurring right now."
Sarkisian's squad seemed ready to break the trend when the Huskies handed Stanford its lone conference loss last season, a 17-13 setback in Seattle. Instead, Washington lost to Oregon the following week and finished with a mediocre 7-6 record. Stanford went on to beat the Ducks and win the Pac-12 and the Rose Bowl.
Both teams have made massive strides since they last met.
The Cardinal failed to score an offensive touchdown and often looked lost under quarterback Josh Nunes at Washington last year while they adjusted to life without Andrew Luck. Mobile quarterback Kevin Hogan took over late last season to spark Stanford's surge and is 9-0 as the starter.
"Schematically, we're not really different," Stanford coach David Shaw said. "Our personnel is different. To have that mobile quarterback is big."
The Huskies, who allowed Stanford to run for a school-record 446 yards in a 65-21 whipping of Washington in 2011, are a totally different team now.
Washington now has the fourth-best scoring defense in the nation (10.8 points per game) under second-year coordinator Justin Wilcox. And the offense features four elite playmakers - quarterback Keith Price, tight end Austin Seferian-Jenkins, running back Bishop Sankey and wide receiver Kasen Williams - and an improved line.
But Stanford, which has won 12 straight games and 11 in a row at home, will present a far tougher test than Washington has faced this season - and an opportunity to rejoin college football's heavyweights. The Huskies haven't started 5-0 since 1992.
"This is right where we want to be, contending for a Pac-12 championship," Price said. "And this is the first obstacle, one of the best teams in the country."
Here are five things to watch when Washington and Stanford meet Saturday night:
THE DEEP BALL: Stanford, known best for its power running game, has forced defenses to back off the line by shifting its passing attack from short and intermediate throws to tight ends to deep balls to wide receivers. Hogan found Devon Cajuste for touchdowns of 57 and 33 yards and hit Michael Rector on a 45-yard TD in a 55-17 win over Washington State last week.
WASHINGTON'S WORKHOUSE: Sankey leads the nation with 151.8 yards rushing per game. He's run for at least 100 yards in seven of his last nine games and will likely need another strong performance to slow down Stanford's relentless pass rush. Sankey ran for 144 yards against the Cardinal last season.
EFFICIENT QBs: Hogan (174.6) and Price (173.6) enter the game with the Pac-12's highest passer ratings. Hogan has completed 63 percent of his passes for 832 yards and 10 touchdowns with three interceptions this season. He also is Stanford's third-leading rusher with 124 yards. Price has completed 72 percent of his passes for 1,044 yards and nine touchdowns with two interceptions. He also has run for 67 yards and a TD in Washington's up-tempo offense.
DEFENSIVE DOINGS: For all the offensive diversity, the defenses have shown up big for both. Stanford has held opponents to 20 points or fewer in 13 of its last 16 games and forced a turnover in 28 straight, the second-longest streak in the country. Washington has gone from the 108th (35.9 points per game) best scoring defense two years ago to 39th (24.2 points per game) in 2012 to fourth (10.8 points per game) this season.
PRESSURE COOKER: Neither team has played a close game this season. Stanford eased past San Jose State and Army, held a 29-0 halftime lead against Arizona State and scored 45 straight to go up 48-3 versus Washington State last week. The Huskies have outscored Boise State, Illinois, Idaho State and Arizona by a combined 159-43 in their first four games. Playing under pressure for the first time this season could be a factor if the game is close late.