When asked, neither Oregon State coach Mike Riley nor Stanford coach David Shaw could remember an instance when two top-15 teams were squaring off this late in the season -- with so much at stake -- with both facing turnover at the most important position in the sport.

At Oregon State, Cody Vaz stepped in and won both games for the Beavers with Sean Mannion on the mend for two weeks following minor knee surgery. Mannion returned, only to throw four interceptions against Washington, and Vaz was called in again to replace him last week as the starter against Arizona State. Vaz is now 3-0 as a starter and has completed 55.9 percent of his throws with seven touchdowns to one interception.

At Stanford, Josh Nunes has battled inconsistency since being named the starter in the preseason. Slowly, Shaw started injecting Kevin Hogan into the lineup before giving him an extended tryout last week in a blowout win over Colorado. Hogan flourished and will start his first career game on Saturday when the No. 14 Cardinal host No. 11 Oregon State.

Cody Vaz has won three straight starts for Oregon State. George Frey/Getty Images

"That's an interesting point," Shaw said when asked if he could remember a situation like this, with two highly ranked teams. "Usually, you're in these positions because your quarterback is playing well. But I think both teams, also, have to do what's necessary to help their teams win."

Hogan has attempted 24 total passes in his career, 23 of them coming last week against Colorado, when he was 18-of-23 for 184 yards with two touchdowns. He also brings an option element, which is how he got on the field earlier this season.

"Early on in spring and early training camp, he was not involved in our quarterback battle, but he showed such athletic ability and such arm strength that he played his way into that competition," Shaw said. "As we got closer to the season, I don't think he had the majority of all of our concepts and protections and run checks completely locked in mentally. It just takes a while. But throughout the beginning of the season, whether it was scout team or getting a few reps with the starters, it showed that it started to sink in. That he understood what was going on and he could anticipate and make good decisions."

Speaking of decisions, Riley said it's a tough one when you have to bench a quarterback. Prior to his injury, Mannion had done a much better job of taking care of the football in his sophomore campaign. Leading up to the Washington State game in early October -- the game during which he got hurt, but played through the injury -- he had six touchdowns with one interception. But he tossed three picks against the Cougars, then missed the two weeks before the ill-fated, four-interception journey to Seattle.

"We had an unusual situation in that Sean got hurt and Cody Vaz, who I always thought competed well to be the starter, got the opportunity and took advantage of it," Riley said. "It's a difficult thing to be in, trying to choose between two good guys and two good players. I think both guys can win for our team and we're thankful for the situation. But it's difficult for the guy obviously that isn't getting to play."

The guys that are going to play know what's at stake. Both the Beavers and Cardinal are still very much in the hunt for the Pac-12 North title. The winner likely gets a nice boost in the rankings and emerges as Oregon's top threat for the divisional crown. More important, should the Ducks run the table and advance to the national championship game, the winner of this game could be the next up to fill Oregon's spot in the Rose Bowl.

Both quarterbacks will be tested by outstanding defenses. Stanford and Oregon State rank first and second, respectively, in the Pac-12 in scoring defense with the Cardinal allowing 16.6 points per game and Oregon State yielding just 18.1. They also boast the top two rushing defenses in the league. Stanford is first nationally, allowing just 55.6 yards per game and Oregon State allows 91.8. They are the only two Pac-12 teams holding opposing teams to fewer than 100 yards per game.

And just for a little added pressure, Oregon State cornerback Jordan Poyer and Stanford safety Ed Reynolds share the conference lead with five interceptions apiece.

"It's impressive to watch if you weren't playing them," Riley said of Stanford's defense. "They are very, very talented. They play hard and they are well-coached and they've done an outstanding job. That's why they are leading our league in defense and ranked nationally where they are. It's a tough chore to play against this team."

The Cardinal offensive line -- and Hogan -- will also have to contend with OSU pass-rusher extraordinaire Scott Crichton, who is second in the league with nine sacks.

"They don't give up a ton of big plays," Shaw said of the Beavers' defense. "They play extremely hard. You can't take a play off or they'll hit your quarterback. You can't take a play off blocking somebody because they'll beat you because they don't ever stop coming."