And then there were two.
California's Justin Cobbs hit the shot of the season to end top-ranked Arizona's pursuit of perfection, 60-58, on Saturday night to cap off one of the craziest days of college basketball.
No. 2 Syracuse needed overtime and Rakeem Christmas' long arm to survive at home against Duke. And earlier in the day, I witnessed No. 4 Wichita State get down by 15 at home to Evansville.
For about 10 minutes, the Purple Aces played like the 1985 Villanova Wildcats. And then they went back to being Evansville and Wichita State went back to being Wichita State, cruising to a 14-point win.
But perfection is fragile. Just ask Wisconsin and Ohio State.
This day of upsets got started with Wisconsin, once upon a time a top-five team, losing to Ohio State.
Three weeks ago, that would have hardly registered as a shocker. Both teams were undefeated at the time. But now we live in a world where Northwestern leads Ohio State, Wisconsin, Indiana and Minnesota in the Big Ten standings.
The Badgers lost for the fifth time in six games and their third straight at home for the first time in Bo Ryan's tenure. And the Buckeyes won for only the second time in their last seven games.
Also losing on Saturday: No. 6 Kansas (to No. 25 Texas), No. 8 Oklahoma State (to a Baylor team that had won one conference game), No. 7 Michigan State (to Big East bottom-feeder Georgetown), No. 21 UMass (to Saint Joseph's) and No. 22 Memphis (at SMU).
A couple of weeks ago, most of us felt like we had our heads wrapped around what's going on this season.
Now just about every team in the Top 25 has turned into North Carolina. As in, it's hard to know what to expect day to day.
The Heels, by the way, have now won three straight after starting 1-4 in the ACC.
As for the Arizona Wildcats, they lost on an unbelievable shot and with one of their starters, Brandon Ashley, out for most of the game with an ankle injury.
"We'd always found a way to be on the positive end of it," Arizona coach Sean Miller said, according to the Associated Press, via ESPN. "Tonight in that same moment, we didn't make the shots and we didn't get the big stop."
Even in a down Pac-12, it was unrealistic for them to go undefeated. Same goes for Kansas in the Big 12, and eventually we'll say the same about Syracuse.
Both Arizona and Kansas should be fine (I think). Yeah, I'm pretty sure of that.
But, really, the first day of February should have taught us one thing that we already knew: This is the year of the unexpected.
Embrace the zaniness.
C.J. Moore covers college basketball for Bleacher Report. You can follow him on Twitter @cjmoore4.