The first two rounds of the NCAA Tournament brought a lot of surprises, busting nearly all of the millions of brackets filled out by fans across the country within hours.

Here’s how the first weekend of the ‘Big Dance’ played out:

ACC leads the way

The ACC placed a record six teams in the Sweet 16, dominating all other conferences. The league had a near perfect 12-1 record in the first two rounds. Pittsburg was the only team in the league to fall, losing to Wisconsin in the first round 47-43.

The highest-seeded team an ACC team has beat, though, was No. 7 Dayton, which fell to Syracuse by 19 points in the first round. Nine of the 12 wins came over double-digit seeds.

The Big 12, who started out with seven teams in the tournament, is now down to just three. Iowa State, Kansas and Oklahoma have all survived the first weekend. The Big 10, which also had seven teams in the tournament, is down to just Indiana, Wisconsin and Maryland.

One team remaining

The Pac 12, SEC and Big East, which are the last major conferences with teams in the tournament, are all down to just one team in the tournament. Top-seeded Oregon is the Pac-12 representative, while Kentucky and Villanova round out the SEC and Big East, respectively.

The Pac 12, which started out with seven teams in the tournament, had five teams lose in the opening round. 3-seeded Utah, the only team other than Oregon to make the second round, lost to 11-seed Gonzaga by 23 points.

Gonzaga, which earned an NCAA Tournament bid for the 18th-straight year, is the only team from the West Coast Conference. They will play Syracuse on Friday in the Sweet 16.

Upsets galore

The first rounds of the NCAA Tournament brought several major upsets, too. Perhaps the biggest came when Middle Tennessee upset No. 2-seed Michigan State in the opening round.

Middle Tennessee didn’t just edge out a win over the Spartan; it won convincingly. The Blue Raiders won 90-81, sending an emotional Tom Izzo and player of the year candidate Denzel Valentine to their final press conference of the season.

Little Rock rallied back from a 13-point deficit to upset No. 5-seed Purdue in double overtime. Paul Jesperson of UNI hit a half-court buzzer beater to top No. 6-seed Texas in the first round, and Wisconsin hit a three-pointer at the buzzer to upset No. 2-seed Xavier to earn a Sweet 16 berth.