Florida State’s Mfiondu Kabengele and Braian Angola celebrate their upset of Xavier. (Andy Lyons/Getty Images)

2018 NCAA tournament interactive bracket

Schedule and results | Top story lines | Tournament history

If you were a top-four seed Sunday — heck, if you were a top-two seed — you were in big, big trouble.

The No. 1 seed in the West Region, Xavier, fell to No. 9 Florida State, 75-70, in the day’s final game featuring a top-four seed. When the dust settled, just one of the six teams seeded that high had survived, and second-seeded Purdue barely got past 10th-seeded Butler, winning by just three points.

As with in-town rival Cincinnati, a No. 2 seed that saw seventh-seeded Nevada storm back from 22 points down in the second half, Xavier held what appeared to be a comfortable lead until the late stages. Up 65-56 with six minutes left, the Musketeers let the Seminoles chip away until FSU hit a three with 1:08 left, giving the school its first lead of the second half.

Unlike Nevada, which relied almost exclusively on its starting five, FSU got a wide range of contributions, with Braian Angola’s 16 points leading nine players who score for the school. Xavier’s J.P. Macura led all players with 17 points, but he fouled out with just over two minutes left.

The Seminoles move on to a matchup with No. 4 Gonzaga. With the shocking first-round upset of the top-seeded team in the South Region, Virginia, two No. 1 seeds have failed to advance to the Sweet 16 for the first time since 2004.

West Virginia easily wins in-state battle with Marshall

Advancement in the tournament wasn’t the only thing at stake, so were state bragging rights, and West Virginia handled both with ease. The fifth-seeded Mountaineers easily took care of in-state rival Marshall, 94-71, in the East region.

The final game of a tumultuous Sunday ended things with a relative whimper, at least from competitive and/or bracket-busting standpoint. The No. 13 Thundering Herd proved pesky in the early going, but West Virginia opened a double-digit lead with six minutes left in the first half and poured it on from there.

The Mountaineers’ Jevon Carter led all scorers with 28 points, while his team shot a scorching 12 for 25 from three-point range. Ajdin Penava led Marshall with 18 points, but he could not help his squad spring a second straight upset, following a first-round ouster of No. 4 Wichita State, and West Virginia moved on to face No. 1 Villanova.

UMBC’s Cinderella run ends at the hands of Kansas State

UMBC gave plenty of reason for hope that it could continue its Cinderella run to the Sweet 16, but ultimately, the 16 seed could not quite summon enough to get past ninth-seeded Kansas State. The Wildcats survived a hard-fought game to top the Retrievers, 50-43, and move on in the South Region.

UMBC started the game with a 10-2 lead, and even after KSU rallied, the Baltimore-area school, which shocked Virginia in the first round to spring the NCAA tournament’s first 16-1 upset, would not go away. The Retrievers pulled to within one point at 38-37 with just five minutes left before the Wildcats made some crucial plays down the stretch.

KSU sophomore Xavier Sneed was instrumental in the closing minutes, throwing down two dunks, one off a steal and another on a putback, and hitting a short jumper when points were extremely difficult to come by for both sides. Teammate Barry Brown Jr. led all players with 18 points, while Jairus Lyles, who had 28 against U-VA., paced his squad Sunday with 12, albeit on 4-of-15 shooting.

The Retrievers are out of the tournament, but it will be a long time before their monumental toppling of Virginia will be forgotten. Or, as UMBC’s entertaining Twitter account put it, “Well, it was fun y’all. KState may have won (50-43), but we hope to have won your hearts.”

KSU moves on to a matchup with No. 5 Kentucky, the highest seed left in the upset-strewn South region. Meanwhile, in the wake of its loss, UMBC was the subject of a slew of congratulatory tweets. Here is a sampling:

“It wasn’t meant to be,” Retrievers Coach Ryan Odom said after the game (via The Post’s Gene Wang). “But nothing can take away, this loss can’t take away what … our team has been able to accomplish throughout this entire season, certainly in the NCAA tournament.

“Just to be here is a blessing for sure.”

Clemson crushes Auburn

On a day otherwise filled with huge drama, this game was over early. Fifth-seeded Clemson began pulling away from fourth-seeded Auburn 10 minutes in, and the Tigers never let up, waltzing to an 84-53 victory in the Midwest Region.

With just under 11 minutes left in the game, Clemson had a 72-31 lead, meaning that over the previous 20 minutes it had gone on a 50-16 run. The Tigers made it to the Sweet 16 for the first time since 1997, where they will have a matchup with No. 1 Kansas.

Clemson’s Gabe DeVoe had a game-high 22 points, while Bryce Brown and Mustapha Heron led Auburn with 12 points each. Auburn hit just 17 of 66 shots form the field, for a .258 percentage, while Clemson shot .475 from the field and out-rebounded its opponent, 55-36.

Nevada comeback tied for second-greatest ever in tournament

According to ESPN, Nevada’s 22-point comeback against Cincinnati is tied for the second-greatest ever in the NCAA tournament. Duke also rallied from that many down to top Maryland in the 2001 Final Four, while the record was set in 2012, when BYU came back from a 25-point deficit to beat Iona in a play-in game.

With its 22-point lead with 11 minutes left, Cincinnati had about as high a win probability for the game, 99.9 percent, as possible. But that’s why they call it March Madness, right?

Nevada rallies from 22 down to stun Cincinnati

The tournament’s comeback kings did it again and this latest rally was nothing short of astounding. Down 22 points with 11 minutes to go against No. 2 Cincinnati, seventh-seeded Nevada roared back to shock the Bearcats, 75-73.

The South region has now lost the No. 1, No. 2, No. 3 and No. 4 seeds — all before the Sweet 16. In addition to Nevada, UMBC, Loyola Chicago and Buffalo have all experienced unexpected success in this quadrant of the tournament, leaving No. 5 Kentucky as the highest seed remaining.

The Wolf Pack did it with just a six-man rotation, one of whom, senior Hallice Cooke, took just one shot and barely made a box-score dent beyond committing three fouls. Nevada leaned heavily on Cody Martin (25 points), Josh Hall (14), Kendall Stephens (13), Jordan Caroline (13) and Caleb Martin (10), and they came through in a big way.

Cincinnati was led by by 19 points from Jacob Evans III, but the Bearcats unraveled down the stretch, failing to make a field goal in the final five minutes while committing three turnovers. It hardly helped Cincinnati’s cause that one of its top players, Jarron Cumberland, fouled out with four minutes left in the game.

Nevada, meanwhile, might have been less fazed at being down 65-43 than most teams would have been, especially under the pressure of the tournament. The Wolf Pack could draw on its experience in the first round, when it rallied from a 14-point second-half deficit to beat Texas, 87-83, in overtime.

Texas A&M routs North Carolina

A harrowing day for high seeds continued into Sunday evening, as No. 2 North Carolina was routed by No. 7 Texas A&M, 86-65, in the West region. That occurred just a couple of hours after No. 3 Michigan State fell to No. 11 Syracuse, with No. 2 Purdue barely surviving No. 10 Butler earlier in the day.

The defending champion Tar Heels’ 21-point loss made for Coach Roy Williams’s largest margin of defeat in his teams’ NCAA tournament history. After UNC took a 20-13 lead with 11:35 to play in the first half, the Aggies pulled even, then pulled away and the game was never close after that.

Four players scored in double figures for Texas A&M, with freshman T.J. Starks leading the way with 21 points and two others adding eight points each. UNC senior Joel Berry II, who was instrumental in his team’s championship run last year, led his squad with 21 points, but he shot just 2 of 10 from three-point range as the Tar Heels combined to go 6 of 31 from long range.

UNC had major trouble handling the two star big men for Texas A&M, junior Tyler Davis (18 points, nine rebounds) and sophomore Robert Williams (8 points, 13 rebounds). The Aggies now move on to a Sweet 16 matchup with No. 3 Michigan.

Syracuse knocks off Michigan State

The second half of the Syracuse-Michigan State game delivered the suspense that the first half did not, with the No. 11 Orange pulling off the first big upset of the day by toppling No. 3 seed Michigan State.

The Orange emerged with the victory in a battle of fouls and free throws over the last 7.8 seconds with Syracuse up by three points. Michigan could never get ahead, though, and Paschal Chukwu’s free throw with 2.4 seconds left sealed the 55-53 victory.

Remember how Syracuse was given a roughly 50-50 chance of making the tournament a week ago? Now the Orange will play No. 2 seed Duke in a Sweet 16 game Friday, the 19th appearance by Syracuse in the Sweet 16.

You were forgiven if you dozed off in a first half played just the way Jim Boeheim likes it, although it ended in a 25-22 halftime lead for the Spartans. But if you napped, you missed a game that went from mild to wild as Matt McQuaid fielded his own missed field goal and heaved up the buzzer beater.

Haas out, Haarms in: Isaac Haas, Purdue’s 7-foot-2 center, gave it his best shot, warming up Sunday with a bulky black brace on the right elbow he fractured two days ago, but the NCAA ruled that he could not play against Butler.

As it turned out, 7-3 backup Matt Haarms filled in admirably and the Boilermakers held on for a 76-73 victory that sends them to a Friday game in Boston against Texas Tech in the Sweet 16. Vincent Edwards led Purdue with 20 points.

“Next man up, next man up,” Haarms, and his magnificent head of hair, told CBS. “[Haas] was a great voice for us on the bench, mentoring me. … This was for him. I’m so excited right now. I’m so happy. … It’s on to next week.”

Purdue previously had ruled Haas out for the rest of the tournament, but the NCAA was definitive, determining that the brace did not meet the safety standards outlined in its rule book.

Schedule and results (All times Eastern):

If you’re wondering where one of the most adorable mascots in sports was, Butler Blue III, the school’s mascot, was denied admittance to the arena because NCAA rules (those again) bar live mascots during the early rounds, when so many teams and so many games make for a chaotic scene for humans, let alone animals. Schools can ask for an exception for the Final Four, but this good doggie is headed home.

Higher powers, if not higher seeds, at work: “By the grace of God, I made the shot.” — Michigan’s Jordan Poole, after his buzzer beater stunned Houston early Sunday morning.

There’s been a lot of that going around. If last year’s rather predictable early days of the NCAA tournament lulled fans, this year’s is demanding attention for every single game. Just look at Saturday.

There was third-seeded Michigan advancing to the Sweet 16 early Sunday morning, holding off an upset bid by No. 6 Houston hours after No. 11 Loyola Chicago stunned No. 3 Tennessee with a buzzer beater of its own. The Ramblers won with a buzzer beater, too. A higher power might have been at work here, as well, summoned by 98 year-old team chaplain Sister Jean Dolores-Schmidt.

“I told them we were going to win and we could do it and God would be on our side,” Schmidt told TNT.

It’s as if teams suddenly remembered and began believing in themselves and the power of possibility after watching UMBC (Maryland Baltimore County for those who have been asking) shock Virginia late Friday night.

If a No. 16 seed can knock off a No. 1 for the first time in men’s tournament history, why not us, they seem to be reasoning.

Sunday brings another day of possibilities. We’re looking at you now, Butler, Syracuse, Texas A&M, Nevada, Clemson, UMBC, Florida State and Marshall. With brackets thoroughly busted, why not root for the underdogs?

UMBC has a new fan: The Chesapeake Bay Retrievers (very, very good dogs) will try for another upset against Kansas State and there’s one very high-profile newbie on the pooches’ bandwagon now, a certain Green Bay Packers quarterback named Aaron Rodgers who admitted in a tweet “#umbcfannow.”

He hopped aboard after Zach Seidel, who runs UMBC’s fabulous Twitter account, mentioned that Joe Sherburne, who is from Whitefish Bay, Wis., is a fan of the QB. Sherburne, in fact, imitated Rodgers’s celebratory discount-doublecheck championship belt move after scoring Friday night.

Bill Murray, superfan: The actor is likely to be playing the role of rumpled fan/supportive dad again Sunday night as Xavier, where his son Luke is an assistant, takes on No. 9 Florida State. Xavier, we must remind you, is a No. 1 seed. Best of luck, Bill. If recent history is any guide, Xavier is gonna need it.

Top story lines

— So … UMBC, huh? A school’s whose rising academic reputation may have been lost on most of the country suddenly finds itself in a national spotlight, despite Sunday’s truTV billing. School President Freeman A. Hrabowski III is an activist, innovator and “mega nerd,” but as The Post’s Jerry Brewer writes, Hrabowski’s latest role is “Giddy basketball fan.” Perhaps the biggest breakout star of the weekend was Zach Seidel, a 27-year-old alumnus of the school whose irreverent but joyous tweeting attracted legions of supporters. And don’t forget about Jairus Lyles, a DeMatha graduate who, with his teammates is carrying the flag for Maryland basketball this week. And check out his high school roster.

— No. 13 seed Marshall is an underdog against fifth-seeded West Virginia, but the matchup may be less one-sided than you think. Led by Dan D’Antoni, brother of Houston Rockets Coach Mike, the Thundering Herd rely on an NBA-flavored offense that prioritizes three-pointers and layups, and relies on incessant and relentless picking and rolling. Sunday’s game will provide a fascinating test for the Mountaineers.

— Clemson vs. Auburn is a football semifinal, right? There has to be tailgating before this game, right? And the winner will face some other Southern power for a national championship, right? (Wrong: The winner will actually play No. 1 seed Kansas. Good thing for Jayhawks fans this isn’t actually a football tournament.)

— No. 10 seed Nevada survived a first-round game that looked hopelessly lost, but as The Post’s Chuck Culpepper wrote, the Wolf Pack’s rally from 14 points down was “yet another indicator of a strong stomach.” It was Nevada’s first NCAA tournament win in 11 years. Up next: Cincinnati.

— Among Saturday’s second-round highlights: Loyola Chicago moving on to the Sweet 16 thanks to a go-ahead bucket in the final seconds. And that will mean another week of temporary fame for Sister Jean Dolores-Schmidt, 98, the team’s chaplain and one of this tournament’s most compelling characters.

— Defending champs North Carolina will attempt to get back to the Sweet 16, with seventh-seeded Texas A&M standing in the way. The Tar Heels are looking for a third straight Final Four berth, and as Brewer found out, Coach Roy Williams is preaching fun above all. Don’t take any of this for granted: “Every win, every round, warrants a little revelry,” Brewer writes.

— Wondering what’s most likely to happen next? The Post’s Neil Greenberg continues to update his live tournament odds, which now reveal that Duke has a 49 percent chance of advancing to the Final Four.

Tournament history