Inconceivable because the Golden Bears hadn't put together consecutive wins in conference play this season, let alone defeated a team above them in the conference standings.
Inconceivable because the Ducks arrived in the Bay Area on Wednesday without a conference loss and two games ahead of teams it would not have to play again this season.
And yet Cal washed away its early struggles with the 58-54 win Saturday, Oregon washed away its early advantages, and the Pac-12 race was essentially reset at the halfway point of the conference schedule like sand on a beach after the water recedes.
Now Cal is in a position to again become a legitimate player in the conference because it remembered what it takes to win games, defense. Tenacious, relentless, body-on-body, hands in passing lanes, championship defense.
It was the kind of defense Cal played Thursday night as it rallied back to defeat Oregon State. Taking inspiration from that result, it finally delivered a full game's worth of effort and intensity in the finest performance of the season.
"We figured we have to play like that for 40 minutes and not just 20 minutes and we'll get a better outcome," said forward Richard Solomon, who had 13 points and 12 rebounds. "I think it showed."
Aside from shooting percentage – Oregon made 20-of-42 shots from the field – it was the lock-down defense Cal delivered in every other aspect of the game that set the stage for the 10-0 run to close out the game.
Cal allowed just six fast-break points and three second-chance points, exceeding the goals head coach Mike Montgomery had set during an hour-long practice Friday.
When Cal couldn't hit a shot to start the game, making just three of its first 15 shots from the field, it channeled that frustration into the other end so Oregon couldn't pull away.
When Oregon seemingly pulled away for good with a 9-0 burst to build an eight-point lead with 6:33 left to play, Cal clamped down again. Oregon made only two of its final seven shots, missing its last five shots from the field, and committed four turnovers, including the steal by Tyrone Wallace that led to Allen Crabbe's layup to tie the game at 54-all with 2:32 to go.
"I thought everybody was tuned in and geared to playing defense at the end," Montgomery said. "They were not going to give in."
Defense created points in that fashion all day, allowing Cal to overcome its own poor offense. 22 Oregon turnovers led to 25 points, buttressing the 15-of-48 shooting from every player not named Crabbe.
"We realize if we play defense, the offense will take care of itself," Solomon said.
Now Cal will find itself in no worse that a tie for fifth place at the end of the weekend. Move up one more spot by year's end, and there will be the added bonus of a first-round bye in the conference tournament, but loftier goals of a regular-season title are back in play.
"Even before the season started, I thought the ceiling for this team was really high," forward David Kravish said. "We just had to figure ourselves out and put it together because we have got all the parts. I really think in this game it showed what we can do when we put it together, especially on the defensive end."
However, there is no time for Cal to get too full of itself. There are road games at the Arizona schools next week, then a visit from UCLA, playing the top four teams in the conference in a 13-day span.
While they will appreciate the help – all three already lost their only regular-season games against Oregon – none will reward Cal by lying down, something Kravish already acknowledged.
"This win and Oregon State were really important to show us how we have to play," Kravish said. "Arizona State and Arizona are really good teams, so if we are going to win those games we got to come out with the same energy, the same intensity on defense."
Cal has finally found its flow, a defensive wave that can take it as far as anyone can imagine.
Dan Greenspan writes about the Pac-12 for Fox Sports Next. Follow him on Twitter @DanGreenspan.