Arizona lost a game and most likely its No. 1 ranking.
Now the Wildcats will have to finish the season without one of their top players.
Forward Brandon Ashley is out for the season after injuring his right foot in a 60-58 loss to California, a game that will likely knock the Wildcats down the rankings after eight straight weeks at No. 1.
[RECAP: Cal upsets No. 1 Arizona]
"Last night, early in our Cal game, Brandon Ashley suffered a foot injury that will end his season," Arizona coach Sean Miller said in a statement Sunday. "While we're all disappointed, we are also aware that Brandon needs our support and positive energy surrounding him. Someone once told me, the hottest heat forges the strongest steel. This adversity will ultimately make Brandon and our team stronger moving forward."
Arizona (21-1, 8-1 Pac-12) went into the game on a school-record 21-game winning streak after holding off Stanford on Wednesday to start the two-game Northern California swing.
Few things went right for the Wildcats in the second half of the trip.
Arizona had a rough night shooting, couldn't get stops when they needed them down the stretch and junior guard Nick Johnson, the team's catalyst, had a rare off night.
The worst news was the injury to Ashley.
Ashley injured his right foot grabbing a rebound in the opening minutes and didn't return, spending the second half wearing a walking boot and on crutches.
He has been crucial to Arizona's run this season, an athletic player who can score, rebound, hit shots from the perimeter when needed and guard just about every position on the court.
Now, the Wildcats will have to figure out how to play without him.
"For us, we have to figure out from the bench perspective of getting a few guys who haven't played as much - some maybe not even at all - they have to start getting the opportunity," Miller said. "That opportunity doesn't have to be 20 minutes a game, but it might need to be a four-minute window or a couple of minutes here and there."
The Wildcats' run this season had been characterized by their ability to pull out tight victories by clamping down on defense and hitting big shots, even on nights when they didn't shoot well.
Arizona has struggled with its perimeter shooting at times this season and had another rough night from beyond the arc, hitting 2 of 11. The Wildcats had trouble inside, too, fighting against Cal's defense and missing some relatively easy shots while shooting 32 percent overall.
Arizona had been able to clamp down defensively on teams late in games to pull out victories numerous times this season, including the victory over the Cardinal. The Wildcats tried to do it again against the Bears, but fell short, losing when Justin Cobbs hit a fallaway jumper with 0.9 seconds left.
The loss leaves No. 2 Syracuse (21-0), the likely new No. 1, and No. 4 Wichita State (23-0) as the only unbeaten teams in Division I.
"Because we've been in this situation so many times, we're really comfortable. We weren't worried at all. We were ramped up," said Arizona center Kaleb Tarczewski, who had a career-high 18 points. "Cobbs made a really, really tough shot."
It didn't help the Wildcats that Johnson wasn't able to carry them for one of the few times this season.
He tried to pick up the slack with Ashley out, but wasn't able to do it, scoring four points on 1-of-14 shooting.
"Tonight wasn't his night," Miller said. "One for 14, 0 for 5 (from 3-point range) and five turnovers. But part of us being 21-0 and 21-1 is how well he played. We needed a couple of guys to step up."
And they made need it to continue with Ashley likely out for a while.