North Dakota State junior guard Lawrence Alexander and his 28 points reminded everyone why the NCAA men’s basketball tournament is nicknamed "March Madness."

Making the second appearance in school history, the No. 12 seed Bison provided the biggest upset during Thursday’s opening day with an 80-75 victory over No. 5 seed Oklahoma.

It wasn’t the only upset with No. 12 seed Harvard eliminating No. 5 seed Cincinnati 61-57, and No. 11 Dayton upending No. 6 Ohio State 60-59 despite a last second runner in the lane from senior guard Aaron Craft.

N.D. State and Harvard join the long list of 12-seeds to topple a 5-seed, and according to CBS Sports only three times in the last 29 years since the tournament expanded to 64 teams has a No.12 not upset a No. 5.

The Sooners could take solace in that fact, but after finishing second in the Big 12 and making its first appearance in the tournament since 2009’s Elite Eight, many will say they choked.

Before tip-off, the Bison weren’t the biggest challenge the Sooners had faced this season. During the regular season Oklahoma boasted the seventh highest-scoring offense in the country, and claimed victories over ranked Iowa State, Baylor, Oklahoma State and Texas.

Many of the signs pointed to Oklahoma overcoming their struggles from the floor. The Sooners were dominant on the glass with 18 offensive rebounds to six for the Bison, and only committed 10 turnovers to 15 for N.D. State. Oklahoma was down by eight at the half, and would chisel away at the lead to force overtime, but their 34.7 percent shooting from the field and five missed free throws were the daggers.

Timely shot making from Alexander and freshman guard Carline Dupree in overtime also proved to be the difference. On the season, the Bison were first in the nation in team field-goal percentage at 50.9 percent.

In Dayton’s case, they matched the Buckeyes in nearly every category and proved more aggressive by attacking the basket for five more free throw attempts and makes. That’s without mentioning 10 points off the bench from senior guard Vee Sanford, compared to 11 combined bench points from Ohio State. Sanford also provided the go-ahead lay up up with 3.8 seconds remaining.

Finishing sixth in the Atlantic 10 this season, the Flyers have tried to play Ohio State during the regular season for quite some time and now they’ve given reason to start an in-state rivalry.

Harvard’s win can’t really be called an upset. Winners of the Ivy League title for four straight years, the Crimson pulled away from Cincinnati with a seven-point halftime lead, and earned 12 more trips to the free throw line. Guard Wesley Saunders scored a team-high 12 points, and overall the Crimson shot 43.2 percent from the field, compared to 36.8 percent from the Bearcats.

It was just the second tournament win in Harvard’s history, which is five less than the number of U.S. presidents it can claim as alumni.

Despite their excellent play in the second round, all three schools could struggle with their next matchups.

Next up for Harvard in the East Region is a date with No. 3 seed Michigan State, which won its first game by 15 thanks to a dominant 41 points from senior forward Adreian Payne.

In the West Region, N.D. State takes on No. 4 seed San Diego State. The Aztecs survived their upset bid against New Mexico State on Thursday, and now know what to expect from the Bison.

And in the South Region, Dayton meets No. 3 seed Syracuse and top point guard Tyler Ennis. Though they struggled in the second half of the season, the Orange ripped Western Michigan for a 25-point win in the second round and were one of handful of teams ranked No. 1 overall this season.