The citizens of Beaver Nation have agonized long and hard, but it sounds as if they’ve finally made their peace with a cold, hard truth:

The time has come for Beavers fans to root for their archrivals, the Oregon Ducks, to win a football game.

That time comes on Saturday, when the Ducks head to Arizona for the week’s crucial Pac-10 game. If the Ducks beat the Wildcats — not, by any stretch, a given — and if the Beavers beat Washington State this weekend (again, not a given, but a better bet), that clears the way for a Civil War game in which the winner claims a berth in the Rose Bowl.

That possibility seemed a little distant a week ago, but some of the necessary pieces snapped into place over the weekend: California beat Arizona, pasting a second conference loss onto the Wildcats. The Ducks beat Arizona State to stay in first place. The Beavers, for their part, whipped Washington to stay in the Pac-10 race with just two conference losses.

A suddenly resurgent Stanford also has just two conference losses, but the Beavers already have beaten the Cardinals, so the Beavers hold the tie-breaking edge. (By our calculations, though, Stanford still could go to the Rose Bowl if certain events transpire, but we won’t belabor them here.)

More worrisome is Arizona, also with just two conference losses — and a victory over the Beavers, which gives the Wildcats the tie-breaker edge if those two teams finish tied.

That’s why Beavers fans will be glued to this weekend’s Oregon-Arizona clash — and why many Beavers fans who usually curse the Ducks with every waking breath will be pulling for Oregon: If the Ducks beat Arizona on Saturday, that would be the third conference loss for the Wildcats, and that team would fall out of the title picture.

If that happens, then the Dec. 3 Civil War game in Eugene would pit the Ducks, with one conference loss, against the Beavers, who presumably (assuming, again, that they beat Washington State) would have two conference losses. If the Ducks win the game, they’re the Pac-10 champions outright and earn the trip to the Rose Bowl. If the Beavers win, they would be tied with the Ducks on top of the conference — but the Beavers would go to the Rose Bowl by virtue of the victory over the Ducks.

That’s a delicious possibility for the Civil War and, it seems to us, a fitting climax for the most entertaining and unexpected Pac-10 football season in years.

So that’s why even die-hard Beavers are swallowing hard and hoping for a Ducks’ win this weekend. Don’t expect us to be breaking out the yellow and green clothing, though: That’s too much to ask.

Earlier in the year, in another context, we said that we typically wish the Ducks well in every game they play — with one notable annual exception. So, this Saturday, we’ll be pulling for the Ducks.

On Dec. 3? That’s the exception.