One weekend down, two to go.

The opening salvo in this year’s NCAA men’s tournament ended with many of the bracket’s best teams still alive as we turn the corner to the Sweet 16. While there were enough upsets to go around, the first weekend has been defined by powerhouse performances from many national favorites, led by No. 1 seeds Connecticut and Purdue.

Then there’s the SEC’s postseason thud. The conference strutted into the tournament with massive expectations but has just two teams left standing from the eight that started. On the other end of spectrum are the ACC and Big East, which will have a combined seven teams in the Sweet 16.

Here’s a look at the biggest stories from the first two rounds before the tournament resumes on Thursday with the East and West region semifinals:

Plenty of upsets (as expected)

According to the NCAA, a tournament upset occurs when the winning team is seeded at least five lines below the loser. By this definition, there have been at least 10 upsets in 15 tournaments since the bracket expanded to 64 teams, with a high of 14 upsets (2021 and 2022) and a low of just three (2007).

There have been seven through the first two rounds of this year’s tournament, all coming in the first round:

• No. 13 Yale 78, No. 4 Auburn 76 (East Region)

• No. 11 Duquesne 71, No. 6 Brigham Young 67 (East)

• No. 12 James Madison 72, No. 5 Wisconsin 61 (South)

• No. 11 North Carolina State 80, No. 6 Texas Tech 67 (South)

• No. 14 Oakland 80, No. 3 Kentucky 76 (South)

• No. 11 Oregon 87, No. 6 South Carolina 73 (Midwest)

• No. 12 Grand Canyon 75, No. 5 Saint Mary’s 66 (West)

Overall, 13 teams have won as the lower seed through the first two rounds.

It’s still a very chalky Sweet 16

With a combined seed total of 53, not far off the tournament low of 49 set in 2009 and 2019, this year’s Sweet 16 ranks among the deepest in recent tournament history. It also stands in contrast to the past three tournaments, when the combined seed total was 78 (2023), 86 (2022) and 94 (2021). Both the East and West regions have their No. 1, No. 2, No. 3 and No. 5 seeds in the Sweet 16, with UConn, Iowa State, Illinois and San Diego State in the East, and Purdue, Tennessee, Creighton and Gonzaga in the West. The Sweet 16 has just one double-digit seed, No. 11 North Carolina State, for the first time since 2015 and just the second time since 2008.

A rare collection of top seeds

All four No. 1 seeds are in the Sweet 16, which is rarer than you might think. This has happened just four times in the past 14 tournaments: in 2012 (Kentucky, Michigan State, Syracuse and UNC), 2016 (Kansas, Oregon, UNC and Virginia), 2019 (Duke, Gonzaga, Virginia and UNC) and now in 2024 (UConn, Purdue, Houston and UNC).

Getting all four No. 1 seeds into the Elite Eight is also outside the norm. That’s happened just seven times since seeding began in 1979: in 1987, 1993, 2001, 2007-9 and 2016. Only once have all four No. 1 seeds reached the Final Four. That happened in 2008, with UCLA, UNC, Memphis and national champion Kansas. There have been three No. 1 seeds in the Final Four three different times, in 1997, 1999 and 2015.

What's even more uncommon is having the eight No. 1 and No. 2 seeds in the Sweet 16. This is just the fifth time this has happened, joining 1989, 1995, 2009 and 2019.

The ACC shines

It’s been an epically successful tournament for the ACC. The conference is 8-1 overall and has four teams in the Sweet 16 in UNC, No. 4 Duke, No. 7 Clemson and N.C. State. The one loss for the ACC came from No. 10 Virginia in the play-in round, giving the league a perfect record in the first and second rounds. The four Sweet 16 bids are the most for the ACC since 2019 and come after having just one last March and a combined six across the past three tournaments. In addition, all three of the Tar Heels, Blue Devils and Wolfpack are in the Sweet 16 for just the third time, joining 2005 and 2015.

Purdue turns the page on Fairleigh Dickinson

Purdue has left nothing to chance after last year’s nearly unprecedented loss to No. 16 Fairleigh Dickinson. After a bit of a sluggish start against No. 16 Grambling, the Boilermakers outscored the Tigers 42-23 in the second half to turn a nine-point halftime lead into a 78-50 rout. It wasn’t even that close in the second run against No. 8 Utah State: Purdue shot 55.9% from the field and 47.8% from deep in a 106-67 win. After pulling off a disappearing act last year, senior center Zach Edey notched the first 30-point, 20-rebound tournament game in 29 years against Grambling and had 23 points and 14 rebounds against the Aggies.

Hot-and-cold last hurrah for the Pac-12

First, the good: Pac-12 teams started 5-0 in the play-in and first rounds, with wins by Oregon, No. 2 Arizona (No. 15 Long Beach State), No. 7 Washington State (No. 10 Drake), No. 10 Colorado (No. 10 Boise State and No. 7 Florida). Now the bad: Every Pac-12 team but Arizona was bounced in the second round, with the Ducks falling to No. 3 Creighton in double overtime, the Cougars losing to No. 2 Iowa State and the Buffaloes losing to No. 2 Marquette. The conference will cease to exist in its current form after this academic year, meaning the historic Pac-12 will continue to play men’s basketball for only as long as Arizona advances this month.

A big flop by the SEC

On the other hand, there’s the tournament bellyflop seen from the SEC. The conference had eight teams in the bracket, tied for the most in the country, but had five exit as higher seeds in the opening round: Kentucky, Auburn, South Carolina, Florida and Mississippi State. Texas A&M rolled over Nebraska in the first round but was bounced in overtime in the second round by Houston. That leaves just Tennessee and Alabama still standing in the Sweet 16. The SEC is 5-6 overall after winning nine tournament games last year.

Rough year finally ends for Kansas

Bill Self admitted after the Jayhawks’ second-round exit against Gonzaga (89-68) that he’d been thinking about next season “for the last month.” Who can blame him? It’s been a miserable year for Kansas, which barely sneaked onto the No. 4 line after losing eight games in Big 12 play, the program’s most in a season since Self arrived in 2003. The Jayhawks were lucky to get past No. 13 Samford in the first round (92-89) before getting blitzed off the court in the second half by the Bulldogs.

This article originally appeared on USA TODAY: March Madness takeaways: Sweet 16 chalk, upsets, ACC shines, SEC flops